Heterosis (over mid parent) and "useful" heterosis (over commercial variety H14) estimates were obtained from a line x tester analysis of crosses involving thirteen diverse female parents with two locally adapted varieties H14 (local standard) and J34. Marked heterosis was observed for seed cotton yield, boll number and halo length. The values of positive heterosis and "useful" heterosis for seed cotton yield ranged from 28.1 to 87.0% and 20.1 to 45.5%, respectively. The overall study of heterosis revealed that female parents PRS-72 (USSR), 5904F (USSR) and MCU-5 (Madras Cambodian Uganda Selection, Coimbatore) were among the top three females, showing considerable heterosis in crosses with H14 and J34 for seed cotton yield and fibre properties. The practical difficulties in exploiting the phenomenon of heterosis and possible experimental approaches in upland cotton are discussed.