A high frequency of apoptosis is a conserved hallmark of oocyte development. In C. elegans, about half of all developing oocytes are normally killed by a physiological germline-specific apoptosis pathway, apparently so that they donate cytoplasm to the survivors. We have investigated the functions of CGH-1, the C. elegans ortholog of the predicted RNA helicase ste13/ME31B/RCK/p54, which is germline-associated in metazoans and required for sexual reproduction in yeast. We show that CGH-1 is expressed specifically in the germline and early embryo, and is localized to P granules and other possible mRNA-protein particles. cgh-1 is required for oocyte and sperm function. It is also needed to prevent the physiological germline apoptosis mechanism killing essentially all developing oocytes, making lack of cgh-1 function the first stimulus identified that can trigger this mechanism. We conclude that cgh-1 and its orthologs may perform conserved functions during gametogenesis, that in C. elegans certain aspects of oocyte development are monitored by the physiological germline apoptosis pathway, and that similar surveillance mechanisms may contribute to germline apoptosis in other species.