Combining ability and heterosis were studied in a line x tester cross in tomato (Solanum lycopersicum L.) during 2008 to 2010 at the Experimental Farm, Horticulture Department, Faculty of Agriculture. The experimental materials comprised four lines (females), viz., CLN 2123, CLN 2400A, CLN 2498E, CLN 2400B and two testers (males), viz., peto86, CastleRock and 8F₁s obtained from the crossing testers with each line. Analysis of variance revealed highly significant differences among all the F₁ hybrid means and their respective six parental values for all examined traits. Positive heterosis over better parent was observed in some crosses for most of studied characters except average fruit weight, which had negative values. Heterosis over better parent ranged from 12.7 to 66.2 for total yield. The mean squares due to general combining ability (GCA) and specific combining ability (SCA) were also highly significant. Among parents, peto86 and CLN2498E proved the best combiners for plant height, fruit set. The parents Peto86 and CLN2400A were the best combiners for early and total yield. While, CastleRock cv. was the best combiner for average fruit weight and fruit firmness. The best specific cross combinations were CastleRock x CLN 2123, CastleRock x CLN2400B, Peto 86 x CLN2400A and Peto 86 x CLN2498E for total yield per plant.