Nine accessions of cucumber and Beta alpha cultivars from North Central Regional Plant Introduction Station  (USDA) viz, PI 109483 (25), PI 169352 (24), PI 169395 (23), PI 211117 (32), PI211984 (26) , PI 169392 (20) ,Beta-alpha (B), PI 178885 (2), PI 218036 (3) and PI 390238 (4)  as well as their twenty one F₁ hybrids in a line × tester meeting design  were used in the present study to estimate heterosis percentage (relative to both mid and better parents), potence ratio and combining ability (general and specific) data were recorded for some characters in cucumber (Cucumis sativus L.) beside estimating  resistance to the two – spotted spider mite, Tetranychus urticae Koch. The experiment was conducted at Kaha Research Farm, Kaliobia Governorate under unheated plastic house in three successive seasons, 2015, 2016 and 2017. The obtained results reflected that significant differences were observed between all the studied characters. In some crosses, high rate of parent heterosis and potence ratio values were observed for the traits supporting the over dominance hypothesis. Other degrees of dominance were observed in many crosses concerning some traits. These results revealed that the hybrid vigor is important for commercial production of cucumber hybrid. Estimates of GCA effects showed that the parent PI 109483 (P25) as well as a line showed that it's the best parent for early and total yield while, PI 169352 (24) was the best parent for early, total yield, average fruit weight and fruit length and PI 169392 (20) was the best parent for earliness characters. But PI211984 (26) and Beat alpha were the best parents for reducing number of movable stages of T. urticae. Estimates of SCA effects cleared that the F₁ cross (P23×P2) was the best combination for early, total yield and the period to first female flower anthesis. Also, the F₁ cross (B ×P3) was the best combination for total yield, early yield, main stem length and the average fruit of weight. The F₁ cross (P26×P4) was the best cross for total yield, early yield and number of node carried first female flower. The F₁ cross (P32×P2) was the best cross for reducing number of movable stages of T. urticae, as well as, decreasing the level infestation of the two spider mites on cucumber plants.