After a literature review, the results are presented of studies on 4 systems of cytoplasmic male sterility (CMS), those of the nap (B. napus), pol (Polima), jun (B. juncea) and ogu (Ogura) type, originating respectively from intraspecific swede rape hybrids, the spring variety Polima, male-sterile Indian mustard, and male-sterile radish. The expression of CMS in the first 3 types was similar, showing temperature-dependent variation which was greatest in the nap and least in the jun type, and resulted from absent or delayed differentiation of the male archespore. The ogu type of CMS resulted from tetrad and tapetum degeneration and was stable. There was a high frequency of B. napus genotypes maintaining CMS of the jun and ogu types and restoring fertility in the nap types. Comparatively rare material restoring or maintaining the pol type of CMS was found among double-zero genotypes. Source material was selected for use in a 3-line system of producing hybrid seed of the double-zero type with pol CMS.