Abiotic stress conditions, especially drought and low nitrogen stress, limit maize production in the tropics, where drought and low soil fertility, mainly nitrogen deficiency, frequently occur together, causing significant decline in maize production. Maize inbred lines tolerant to drought and low nitrogen stresses have been developed by the International Maize and Wheat Improvement Center (CIMMYT). The objectives of this study were to 1) investigate the combining ability of inbreds and hybrids, 2) assess genotype x environment interaction across stress conditions and testing locations, and 3) estimate genetic diversity for restriction fragment length polymorphisms, amplified fragment length polymorphisms, and simple sequence repeats in these inbred lines. Fifteen inbred lines of tropical origin with a range of response to abiotic stresses were crossed in a diallel mating design. The resulting 105 hybrids were evaluated under well-watered, water-stressed, and low nitrogen conditions in a replicated alpha-lattice design. Measurements for grain yield, anthesis silking interval, and ears per plant were taken in each environment. Effects of general combining abilities (GCA) and specific combining abilities (SCA) were estimated following Griffing’s diallel analysis. Both GCA and SCA effects across locations were significant for all the traits. Effects of the interaction of GCA x environment and SCA x environment were significant for grain yield, anthesis silking interval and ears per plant. Inbred CML 258 had the highest GCA for grain yield under water-stressed conditions and across locations. Inbred P501c1 had the highest GCA for grain yield under low N conditions. Hybrid CML 258 x CML 343 had the highest grain yield (4.1 t ha–1) across locations. Data from DNA markers will be analysed to estimate polymorphic information content and genetic diversity and to calculate genetic distance.