The present survey reviews the current knowledge on comma-shaped anaerobic rods that can be isolated from the human genital tract. It summarizes bacterial characteristics such as morphology, biochemical activities, gas chromatographic patterns and differential diagnostic tests. In particular the existence of two variants of such rods is stressed. These variants differ in length, number of flagella, certain biochemical activities and susceptibility to nitroimidazoles. The occurrence of comma-shaped rods in relation to clinical findings is also discussed.