The objectives of this work were to study the effect of plant phenological stage on the ability to tolerate water stress and its effect on plant growth and grain production in several genotypes of grain sorghum. Three contrasting genotypes (UAT 124, UAT 152 and UAT 30) of grain sorghum (Sorghum bicolor L. Moench) were treated with water stress. Drought applied before anthesis accelerated the phenological development between panicle initiation and anthesis, while drought applied during any other phenological stage delayed physiological maturity. Biomass production and grain yield were reduced by water stress but the amount of reduction depended on the genotype and on the phenological stage during which drought occurred. The three genotypes tested differed with respect to ability to recover after drought treatment, mostly due to differences in biomass accumulation, attributed mainly to differences in the maintenance of a greater active leaf area mostly during panicle initiation and flowering. Our findings show that the identification of sorghum genotypes resistant to drought should be conducted by applying drought during the most sensitive phenological stage and using biomass as a criterion selection, especially during the period of post-drought recovery.