It is well known that cyanobacteria produce several toxic compounds. Microcystins, nodularins and cylindrospermopsin are known as the lethal hepatotoxins which are produced by some species of cyanobacteria. In the present study we focused on the biosynthetic relationship between microcystins and other types of peptides produced by toxic cyanobacteria. Here we report that two types of novel cyclic peptides, anabaenopeptins and anabaenopeptilides, were isolated from two Anabaena strains (A. circinalis 90 and A. lemmermannii 202 A2/41) that co-produces microcystins. Their structures were determined by 2D-NMR techniques and the advanced Marfey's method. Anabaenopeptins A〜D (1〜4) are unique cyclic peptides that have the common cyclic pentapeptide moiety, cyclo-(ε-Lys-Val-Hty-N-MeAla-Phe), linked with to Tyr, Arg, Lys and Phe, respectively via the ureido bond. Anabaenopeptilides 202-A (7) and -B (8) are 19-membered depsipeptides that have the following sequence: N-formyl-Pro-Gln-Thr(II)-Hty-Ahp-Thr(I)-N,O-diMeTyr (or Chloro-N-MeTyr)-Ile and the hydroxy group in Thr(II) is combined with the carboxyl group at the C-terminus via an ester bond. Anabaenopeptilides 90-A (5) and -B (6) have the common cyclic depsipeptide moieties to those of 7 and 8, but lack only Pro.