A mutation near cysB on the Bacillus subtilis chromosome marks a new sporulation locus, spoVIC. It causes spores to germinate more slowly than those of the wild-type under all conditions and, from indirect evidence, it does not appear to alter the affinity for the germinant L-alanine. The mutant spores have some deficiency of coat proteins (particularly the alkalisoluble coat protein, Mr = 12 000) and the spore coat layers are disorganized. The mutant strain grows normally and sporulates normally until stage II, after which its sporulation is delayed by about 2 h compared to that of the wild-type. This delay results in the prolonged synthesis of some coat proteins and the late synthesis of others. The abnormal coat may be the cause of the germination deficiency. A double mutant strain carrying the spoVIC610 mutation together with gerE36 sporulates slowly. Its spores have very little coat protein, are sensitive to heat, lysozyme and organic solvents, but germinate as well as the strain carrying the spoVIC mutation alone. The role of the spore coat in germination is discussed in the light of these findings.