Abstract: Yield potential of six onion (Allium cepa L.) cultivars (Red Creole, Chiltan-89, Local, Sariab Surkh, White Globe and Local Kandhari) was evaluated in thrips infested and control environment at Quetta, Balochistan, Pakistan. The results of the trial revealed that Thrips tabaci Lindeman (Thysanoptera: Thripidae) is the attacking species to onion in the region. The said pest infested more or less all varieties. Local Kandhari followed by Sariab Surkh were the most susceptible to thrips infestation while Chiltan-89 was the least. Red Creole and White Globe were discarded due to their poor performance in terms of yield. Maximum yield (12250 Kg ha-1) was obtained by Chiltan-89 while maximum % increase in yield was observed in Sariab Surkh and Local Kandhari (18.6 and 16.69%, respectively). Results of the study showed that Chiltan-89 is the best onion cultivar for the region regarding minimum thrips infestation and maximum yield. But Sariab Surkh and Local Kandhari have great potential of yield in thrips controlled environment. The elimination of thrips could improve the onion yield up to 19%.