The programs offer the possibility of comparing pairs of homologous sequences in order to find out percentage of homology, number of identical and deviating nucleotides, of transitions and transversions and, derived from these, KNUC-values according to Kimura (1) and the corresponding standard error sigmaK. The sequences can be printed in pairs underneath each other, homologies are indicated by asterisks between the identical nucleotides. Out of a set of homologous sequences stored on a disk any number of sequences can be compared in pairs in this way, and a matrix containing either the percentage of homology values, the number of deviating nucleotides or the KNUC-values together with the corresponding standard errors can be sent to screen, printer or disk. A program will be available soon which creates a dendrogram representing the similarity between the sequences by use of an average linkage clustering method deduced from this matrix. The programs are written for Apple II computers using UCSD-PASCAL and for Sirius I/Victor 9000 computers using TURBO-PASCAL.