Six diverse lines of tomato were crossed with six testers in line x tester mating fashion to study heterosis relative to mid parents, better parent and check hybrid and combining ability for some plant and fruit characteristics. The experiment work was conducted at the Exp. Farm, Fac. of Envir. Agric. Sci., El Arish, Suez Canal Univ., Egypt, during the period from 2012 to 2014. For heterotic effect, heterosis over mid-parents, better parent and check hybrid were detected in many traits, viz.; plant height, number of branches, total yield/plant and total fruit number. On the other hand, no heterosis was detected for fruit firmness based on check hybrid. The magnitude of SCA variance was greater than GCA variance suggesting the predominance of non-additive gene action for all studied traits. Among the lines, the good general combiner was AVTO9802 for total yield/plant and fruit firmness and AVTO1008 for average fruit weight. Among six testers, Super Marmand exhibited the highest significant GCA effects for plant height and number of branches/plant, FM–9 was the best for total yield/plant and Castle Rock for average fruit weight and fruit firmness. The estimates of specific combining ability effects (SCA) show superior specific combinations, AVTO1003 x Super Marmand for plant height, AVTO1002 x Peto 86 for number of branches, AVTO1003 x Rio Grande for total fruit number, AVTO0101 x Super Strain B for average fruit weight, AVTO1002 x Super Marmand for TSS%, AVTO0101 x Castle Rock for ascorbic acid content and AVTO1002 x Rio Grande for fruit firmness. Therefore, from general and specific combining ability and some genetic parameters suggested the importance of heterosis breeding for effective utilization of non-additive genetic variances, which had predominant role for the improvement of for some plant and fruit characteristics traits in tomato crop.