Stability of a cytoplasmic male sterile (CMS) line is of the utmost importance for hybrid rice to be commercially useful. In this study, 20 IRRI CMS lines (IR66707A carrying Oryza perennis cytoplasm and all others carrying wild abortive [WA] cytoplasm imparting male sterility) and 13 locally developed CMS lines (all WA-derived) were evaluated for male sterility, days to 50% flowering, plant height, anther color, and grain type at PAU in Kapurthala during the 1996 kharif (wet season). The seeds of CMS lines were produced by hand pollination on a paired plant basis. Each CMS line was planted in paired rows of 12 plants. Spacing between rows and among plants was 20 cm. During flowering, anthers of 5-10 spikelets from two tillers of each plant were squashed and pollen grains were stained with 1% IKI solution and observations for sterile (unstained) pollens were made from five or six microscopic fields. Two panicles of each plant were also bagged before anthesis to study their spikelet fertility at maturity. Based on the degree of male sterility, a CMS line was termed as completely sterile, highly sterile, sterile, partially sterile, or partially fertile.