OsDMC1 is the rice homologue of the yeast DMC1 gene. Here, we analyzed the function of OsDMC1 in meiosis using an RNA interference approach. The OsDMC1-RNAi lines grew normally during their vegetative phase but showed spikelet and pollen sterility. The sterility phenotypes were associated with down-regulated OsDMC1 transcript and protein levels mediated by RNAi. Further cytological observations of male meiocytes revealed that knock-down of OsDMC1 led to defects in bivalent formation and subsequent unequal chromosome segregation and irregular spore generation, and induced changes in male meiotic progression. Fluorescent in situ hybridization experiments revealed that the OsDMC1-RNAi lines were defective in homologous pairing. These data indicate that OsDMC1 is essential for rice meiosis and plays an important role in homologous pairing.