Abstract The potency of samples of Indian Daboia (Russell's viper) and Naia tripudians (Indian cobra) venoms has been compared with that of African viperine and colubrine venoms. Strong solutions of both Indian venoms may be detoxicated and converted into anavenoms by the same methods evolved by us for treating African venoms. The anavenoms retain their antigenic properties as shown by the immunization of laboratory animals, but from the results obtained on a necessarily small number of animals it would appear that the antigenic value of the Indian cobra anavenom is not relatively as high as that of Cape cobra anavenom. The venoms of Daboia and Bitis arietans are so antigenically dissimilar that neither African not Indian concentrated antivenenes exert any appreciable neutralizing action on the heterologous venom. A comparable lack of action was observed when a sample of South American anti-rattlesnake serum was tested against puff adder venom. The colubrine venoms, Indian cobra and Cape cobra, appear to be very closely allied ; Indian concentrated antivenene exerts a moderate group action on Cape cobra and other African colubrine venoms, whilst concentrated African antivenene exerts an even more powerful neutralizing action against Indian cobra venom than it does against the Cape cobra venom from which it was produced. A final point of interest is the fact that antivenenes of a comparable cross potency, as far as colubrine venoms are concerned, may be produced on the one hand by the use of unmodified venoms and on the other by employing only formalized anavenoms ; this furnishes further evidence of the practical utility of the rapid method of producing African polyvalent antivenene of high potency, as successfully employed in our Serum Department during the past 3 years.