The frequencies of alleles responsible for colour of cat fur were studied by method of house-to-house survey in a population of domestic cats in northern Moravia, Czechoslovakia.Of the total of 249 adult cats examined, 114 animals were males and 135 females, the sex ratio being 0.458. The following allelic frequencies were recorded: 0 ----0.016, a = 0.646, t b = 0.288 and S = 0.237. No other alleles were recorded in the phenotype. The results are compared with other populations in Czechoslovakia and other European countries.