J. Michael Hansen
Executive Vice President and Chief Financial Officer at Cintas
Thanks, Todd, and good morning. Our fiscal 2024 first quarter revenue was $2.34 billion compared to $2.17 billion last year. The organic revenue growth rate adjusted for acquisitions and foreign currency exchange rate fluctuations was 8.1%. Gross margin for the first quarter of fiscal '24 was $1.14 billion compared to $1.03 billion last year, an increase of 11%. Gross margin as a percent of revenue was an all-time high, excuse me, up 48.7% for the first quarter of fiscal '24 compared to 47.5% last year, an increase of 120 basis-points.
Strong volume growth and continued operational efficiencies helped to generate this record gross margin. Energy expenses comprised of gasoline, natural gas and electricity or a tailwind, increasing 50 basis points from last year. Please keep in mind that some of the energy benefit is the result of efficiencies we've created with our proprietary SmartTruck technology. Certainly, we have also seen a benefit from a drop in prices at the pump compared to a year-ago.
Gross margin percentage by business was 48.1% for Uniform Rental and Facility Services, 55.9% for First Aid and Safety Services, 49% for Fire Protection Services, and 38.7% for Uniform Direct Sale. Operating income of $500.6 million compared to $440.1 million last year. Operating income as a percentage of revenue was 21.4% in the first quarter of fiscal '24, compared to 20.3% in last year's first quarter, an increase of 110 basis points. Our effective tax rate for the first quarter was 19.2%, compared to 14.8% last year. The tax rates in both quarters were impacted by certain discrete items, primarily the tax accounting impact for stock-based compensation.
Net income for the first-quarter was $385.1 million compared to $351.7 million last year. This year's first quarter diluted EPS of $3.70 compared to $3.39 last year, an increase of 9.1%. Cash flow remains strong. Net cash provided by operating activities in the first quarter grew 13% over the prior year. On September 15th, we paid shareholders $138.3 million in quarterly dividends, an increase of 17.8% from the amount paid the previous September.
Todd provided our annual financial guidance. Related to the guidance, please note the following. Fiscal '24 interest expense is expected to be $98 million compared to $109.5 million in fiscal '23, predominantly as a result of lower variable rate debt. Our fiscal '24 effective tax rate is expected to be 21.3%, this compares to a rate of 20.4% in fiscal '23. The higher effective tax rate negatively impact fiscal '24 EPS guidance by about $0.16 and diluted EPS growth by about 120 basis points. Our financial guidance does not include the impact of any future share buybacks. Guidance includes the impact of having one more workday in fiscal '24 compared to fiscal '23. This extra workday comes in our fiscal third quarter. Jared?