The current study was conducted at Jimma University College of Agriculture and Veterinary Medicine of Ethiopia to find the effect of farm yard manure application rate on yield and yield component of lettuce. The experiment was arranged at three levels of farm yard manure (5 ton/ha, 10 ton/ha and 15 ton/ha). Each treatment was arranged as 1.1 kg, 2.25 kg and 3.3 kg/1.5 m2as T2, T3 and T4 respectively, and the control (0 kg/1.5 m2) as T1. A total of four treatments have been used. As the experimental tests showed that, farm yard manure with the rate of 3.3kg (15 ton/hek) is highly increased the yield and yield components of lettuce (plant height, leaf size, number of leaf per plant, fresh leaf weight, root depth and number of root per plant. Hence, it is recommended for general cultivation of lettuce under Jimma growing condition. Moreover, as the crop is growing at small scale farmer’s level in Jimma area further studies are needed with regard to the improvement of agronomic practices for lettuce at commercial level cultivation in Jimma and similar agro ecology.