In Tanzania, cotton is of great economical importance, representing a large percentage of agricultural exports, but yield and lint quality is still relatively poor. The aim of this study was to identify parents to improve boll and lint yield and quality. Parents and F1 progeny of a 7 £ 7 diallel were evaluated in four diVerent environments. Results indicated signiWcant variation for especially yield components, yield, ginning outturn and Wbre quality. Parents with high and positive GCA like NTA 93-21, Delcot 344, Auburn 56 and MZ561 and combinations with high and positive SCA for the characteristics were identiWed. Additive genetic eVects were seen for most of the characteristics, except for Wbre strength at one locality. Parents with high GCA eVects for certain characteristics produced combinations with high SCA eVects for the same characteristics. This study indicated that there is enough genetic variability for boll and lint yield and quality for eVective selection, and good parents that can be included in the breeding programme.