Line x tester approach with 12 lines and 3 testers was used to assess maize combining ability. The 36 crosses and two checks were tested under regular irrigation and water shortage in RCBD design with three replications. The topcross L9 x M2 performed best for days to 50% silking, while the cross L7 x CIMMYT14 for grain yield plant-1. Non-additive gene action was predominant for all traits and GCA was more stable under varied environmental conditions than SCA. Lines L5 and L8 had favorable GCA impacts for yield and some related characters. Desirable SCA effects for days to 50% were obtained for the cross L9 x M8. The cross L7 x CIMMYT14 and L11 x M8 gave the best SCA values for grain yield plant-1 and one or more other traits. The cross L9 x M8 gave the best heteroboltosis for days to 50% relative to both checks. Moreover, the most desirable heterotic effects for grain yield plant-1 were detected for the crosses L5 x M2 under drought stress and combined data and the cross L7 x CIMMYT14 under normal irrigation relative to both checks.