In order to obtain viscosities of biodiesel fuels at a temperature range from 0 to 100 degrees C in the steps of 10 degrees C, DV-II+ Pro rotary viscosimeter from Brookfield Engineering Co., USA, was used and tests were performed at 20 degrees C ambient temperature. The viscosity measurements were made on a viscosimeter at a 100 rpm constant speed with PC control. The data with the Wingather VII software from Brookfield Engineering Co., USA, were recorded in the computer at 5 second intervals. It is observed that biodiesels are similar to diesel fuels in view of the viscosity properties when the diesel fuel concentration in which biodiesel and the temperature is increased.