In this study dynamic flow rates of a common rail injector using diesel fuel and different biofuels were determined. As biofuels, fatty acid methyl esters originating from canola, poultry, cattle and used cooking oil were tested. The tested fuels exhibited different physical properties e.g. density and viscosity. Measurements of the injector delivery rates were performed on a test stand designed for determination of injectors and injection pumps characteristics. Each fuel was tested at temperatures between 30 and 60°C, under injection pressure in the range of 30–180 MPa and injection time in the rangeof 200–1600 microseconds. The results showed differences in injector flow rates depending on used fuel, however different fuel properties affected amount of fuel injected especially at short injection durations.