The in vitro synthesized sodium azide mutagenic metabolite (azidoalanine) produced single-strand breaks and proteinase K-sensitive sites in isolated, germinating barley embryos. In contrast with sodium azide, the efficiency of DNA damage induction was lower, and both types of DNA lesions were totally or partially repaired in the course of subsequent 24 h incubation of the embryos. The mutagenic azide metabolite did not inhibit DNA replication, while azide did so even at doses which are not highly mutagenic. The metabolite labelled with 14C at the amino acid residue was taken up with a similar efficiency both into barley embryos germinating for 2 days and into cells of Salmonella typhimurium TA100. The majority of the radioactivity was incorporated into proteins, less into RNA and a negligible amount into DNA.