Abstract: For determination of good combiners for physiological heritable traits, a study on a 8x8 diallel fashion in sunflower was conducted during 2003 at NWFP Agricultural University Peshawar Pakistan. The extent of combining ability for days to 50% flowering, days to maturity, achene yield (kg ha-1) and oil content was find out. The General Combining Ability (GCA), Specific Combining Ability (SCA) and Reciprocal Effects (RE) were significant for all the traits except days to maturity where RE were non-significant. The SCA effects were of greater magnitude than that of GCA effects, which showed high contribution of non-additive gene effects. The GCA:SCA ratio also revealed predominance of non-additive gene effects. Among the inbred lines TF-11, ARI and TF-4 were the best general combiners for all these traits. The best combiners for yield were ARI and GUL. The cross combination TF-335xARI was early in terms of days to 50% flowering and maturity. Generally the hybrids TF-4, TF-335, ARI and PESH performed well in nearly all parameters. Reciprocal crosses have higher potential than direct crosses for most of the traits. Both additive and non-additive variances were involved in the characterization of these physiological traits.