Subharmonics, frequency jumps and biphonations are well described as normal elements of the human vocal repertoire. They were found also in the vocalisations of many other mammals such as the Japanese macaques. In this study the repertoire of the Japanese macaques was quantitatively analysed for the occurrence of subharmonics, biphonations and frequency jumps. These phenomena are summarised as irregularities. Calls from animals of two established caged groups were recorded, analysed and judged on the existence of irregularities. In the age class up to 1 year irregularities occur on average with a frequency of 18.6% (max. 45%, min. 3.5%9 10 infants; 2000 calls). Adult female vocalisations during the mating season 'solicitation call') contain on average 25% irregularities (max. 32%, min. 15.9%: 6 females; 726 calls). Vocalisations from aggressive encounters (67 calls) contain no irregularities in adult males and females, but some biphonations and frequency jumps have been found in the calls of juveniles. The ratio of the three phenomena shows an individual specific pattern.