This study reports the results of chemical and chromatographic studies which establish the presence of 3-keto allocholic acid (3kACA) in water extracts from spermiating male sea lamprey, Petromyzon marinus. This is the second compound to be isolated and identified from these extracts. The first was 3-keto petromyzonol sulfate (3kPZS), which was shown to act as strong pheromonal attractant for ovulated females. Some new characterization data on 3kPZS (utilizing an only recently available synthetic preparation of the compound) is also included. The possibility that a mixture of 3kACA and 3kPZS might be a more potent pheromonal attractant than either compound alone is discussed.