Exhibit 99.1

Parker Quarterly Earnings & Outlook Remain Flat; Industrial Operating Income Rises

Cleveland, Ohio: April 15, 2003 – Parker Hannifin Corporation today reported third-quarter net income for the period ended March 31, 2003 of $48.7 million, or 42 cents per diluted share, on sales of $1.65 billion. Realignment costs, including severance and manufacturing relocations, reduced earnings by four cents per diluted share in the quarter. For the same period last year, net income was $52.4 million, or 45 cents per diluted share, on sales of $1.58 billion, including a reduction of two cents per diluted share in realignment costs.

Parker CEO Don Washkewicz noted continued weakness in the company’s aerospace and North American industrial markets. “Our balance sheet remains strong, and we’re maintaining strict controls on working capital and expenditures,” said Washkewicz. “At the same time, we’re seeing positive progress from all the work we’ve done to realign operations and implement the Win Strategy. We just haven’t seen any improvement in the economy.”

Washkewicz said the continuing strength of cash flow from operations enabled the company to make discretionary contributions of approximately $108 million to its pension plans during the quarter in the United States, Canada and the United Kingdom. “This demonstrates the company’s commitment to maintaining well-funded pension plans for our employees around the world.”

Washkewicz also noted that operating income was up in every segment except aerospace, where sales were two percent lower than last year and the operating margin was 13.6 percent.

1

In the industrial segment, operating income was up 20 percent overall. In North America, sales were flat and the operating margin was 5.8 percent. The international industrial business achieved a margin of 5.7 percent with a 28-percent sales increase, mostly driven by currency exchange rates and acquisitions.

In the “Other” segment, sales were seven-percent lower than in the prior year, reflecting the divestiture of the Wynn Warranty business last June, while operating income was up nine percent, and the margin improved to 9.0 percent.

Nine-Months’ Results

Sales in the first nine months of fiscal 2003 were $4.75 billion, up six percent from the same period last year. Year-to-date net income increased to $147.2 million, or $1.26 per diluted share, reduced by 10 cents per diluted share in realignment costs and an equity-investment adjustment. In the first nine months of fiscal 2002, the company earned $142.0 million, or $1.23 per diluted share, for which realignment costs and an equity-investment adjustment reduced earnings by 13 cents per diluted share.

Outlook

The company did not issue a range of projected earnings for the remaining quarter of fiscal year 2003, citing continued economic uncertainties and limited predictability of aerospace and industrial activities in the current climate. “With no discernable change in market conditions, all we can say is that we expect the coming quarter to be very similar to this one,” said Washkewicz.

Parker advises shareholders to note monthly order trends, for which the company makes a disclosure several business days after the conclusion of each month. This information is available on the company’s investor information web site, at www.phstock.com.

With annual sales exceeding $6 billion, Parker Hannifin is the world’s leading diversified manufacturer of motion and control technologies and systems, providing precision-engineered solutions for a wide variety of commercial, mobile, industrial and aerospace markets. The company employs more than 48,000 people in 44 countries around the world. For more information, visit the company’s web site at www.parker.com, or its

2

investor information site at www.phstock.com.

Forward-Looking Statements contained in this and other written and oral reports are made based on known events and circumstances at the time of release, and as such, are subject in the future to unforeseen uncertainties and risks. All statements regarding future performance, earnings projections, events or developments are forward-looking statements. It is possible that the company’s future performance and earnings projections may differ materially from current expectations, depending on economic conditions within both its industrial and aerospace markets, and the company’s ability to achieve anticipated benefits associated with announced realignment activities and strategic initiatives to improve operating margins. Among the other factors which may affect future performance are: changes in business relationships with and purchases by or from major customers or suppliers, including delays or cancellations in shipments; uncertainties surrounding timing, successful completion or integration of acquisitions; threats associated with and efforts to combat terrorism, including the war with Iraq; the impact of Severe Acute Respiratory Syndrome on global travel; competitive market conditions and resulting effects on sales and pricing; increases in raw-material costs that cannot be recovered in product pricing, and global economic factors, including currency exchange rates, difficulties entering new markets and general economic conditions such as interest rates. The company makes these statements as of the date of this disclosure, and undertakes no obligation to update them.

3

PARKER HANNIFIN CORPORATION-MARCH 31, 2003

CONSOLIDATED STATEMENT OF INCOME

BUSINESS SEGMENT INFORMATION BY INDUSTRY

Note: Certain prior period amounts have been reclassified to conform to the current year presentation.

CONSOLIDATED BALANCE SHEET

CONSOLIDATED STATEMENT OF CASH FLOWS