From Chlamydomonas reinhardtii chlorophyll b- and neoxanthin-depleted mutants in the cbnI gene, 15 different revertants were obtained and analyzed. In 13 revertants, the complete recovery of chlorophyll b and neoxanthin biosyntheses to the level of the wild-type strain was shown. In two revertants, the biosynthesis recovery of the studied pigments was incomplete (10 and 30% of wild-type chlorophyll b biosynthesis). Single mutations in nuclear suppressor genes were shown by hybridological analysis to be responsible for the recovery of chlorophyll b and neoxanthins accumulation in most revertants. Revertants were distinguished by the degree of linkage between the suppressor and original mutation in the cbnI gene. By means of tetrad analysis, five strains carrying various mutant alleles of suppressor genes in the background of a normal allele of the cbnI gene were isolated. No allelic specificity of suppression was found.