A field experiment was conducted during rabi seasons of 2008-2009 and 2009-10 to study the effect of potassium and cobalt application on growth, yield and nutrient uptake in lentil. The results revealed that the plant height, branches/plant, dry matter accumulation, pods per plant, test weight, grain and straw yield of lentil and protein content increased significantly up to 90 kg K2O ha-1. However, yields attributes and yield at 60 and 90 kg K2O ha-1 were statistically on par. On the other hand, growth and yield attributes and yield (grain and straw) increased up to 4 kg Co ha-1 and thereafter, declined at 8 kg Co ha-1. The protein content in lentil grain improved appreciably when crop was fertilized with 90 kg K2O and 8 kg Co ha-1 over respective controls. The uptake of K and Co in lentil grain and straw increased significantly with increasing levels of K and Co. The uptake of N and P by lentil grain and straw increased with graded levels of cobalt up to 4 kg ha-1. On the other hand, there was a gradual decrease in S uptake with cobalt levels. Potassium application tended to increase the uptake of N, P and S by the crop significantly over control.