Estimates of genetic parameters are useful since they provide information on the inheritance of characters and help to predict the value of crosses. If the value of crosses cannot be predicted, many crosses need to be made which results in each cross having a small population size, fewer progenies in later generations and a lower probability of recovering good genotypes from each cross. The objectives of this study were therefore i) to estimate genetic parameters from diallel crosses involving five inbred lines: Feres Gama(37), Feleme(68), Mage(07), 1153(28) and 1182(44) that vary for different agronomic characters and ii) to determine the breeding value of the parents so that the progeny performance from crosses involving the best parents could be predicted. Data for agronomic characters were obtained from parents and F1 progenies evaluated in a greenhouse under waterlogged and free drainage conditions. The results highlighted the importance of additive gene action for spike length, number of seeds spike-1 and grain yield spike-1 under free drainage conditions and for days to heading and days to maturity at both treatment levels. Both additive and non-additive gene action were important in the control of grain yield under free drainage conditions. By contrast, estimates of genetic parameters for yield and yield components (except spike length) were very low or negative under waterlogged conditions. Among the parents, Feres Gama(37) and 1153(28) contributed the highest positive GCA effects and comparable SCA variances for yield and yield components under free drainage conditions. Hence, these parents shall be tested thoroughly in order that maximum use of their superior combining ability can be made in future crossing programs for environments free of waterlogging stress. A separate crossing and selection program is suggested for the respective environmental conditions if resources permit.