The flow of seed carried by studded feed roller mechanism is affected by constructional and operational variables and by the levels of vibration produced by soil roughness, large aggregates, small stones, and motion of tractor. The effect of four different vibration levels on flow evenness of wheat and barley was determined for three studded feed roller designs and two seed rates. Coefficient of variation in seed flow evenness was determined in a laboratory experiment. Seed rates were 130 kg ha(-1), 180 kg ha(-1) and 150 kg ha(-1), 200 kg ha(-1) for wheat and barley, respectively. The simulated ground speed was 6.5 km h(-1) in all experiments. While the levels of vibration had no effect on the flow evenness of wheat, the flow evenness of barley was significantly affected by vibration. Increasing seed rate significantly improved seed flow evenness.