The results of extensive surveys of red cell carbonic anhydrase phenotypes in the Asian-Pacific region are presented together with data on the occurrence of three new polymorphisms present only in Australian Aboriginals. Two of these systems are widespread right across the Australian continent, while the remaining one is restricted to members of a single linguistic group in Arnhem Land. Further examples of CA1 3-1 Guam are reported, and also CA1 3-1 Singapore which has an electrophoretic mobility indistinguishable from that of CA1 3-1 Guam. Included in the tabulations are data on other populations outside the Asian-Pacific area and, for completeness, information already published on variants of both CA1 and CA2. In an effort to simplify the nomenclature of carbonic anhydrase variants, a new system is suggested, using numerals rather than letters to distinguish the variant isozymes. Modifications of the electrophoresis buffer system which enhances the very small mobility differences existing between several of the products of the CA1 alleles are also described.