Spore formation of Myxococcus xanthus can occur not only on agar plates during fruiting body formation, but also in a liquid culture by simply adding glycerol, dimethyl sulfoxide, or phenethyl alcohol to the culture. This chemically-induced spore formation occurs synchronously and much faster than that occurring during fruiting body formation. Dramatic changes in patterns of protein synthesis were observed during chemically-induced spore formation, as had previously been observed during fruiting body formation (Inouye et al., Dev. Biol. 68:579-591, 1979). However, the production of protein S, one of the major development-specific proteins during fruiting body formation, was not detected at all, although protein U, another development-specific protein, was produced in a late stage of spore formation as in the case of fruiting body formation. This indicates that the control of the gene expression during chemically-induced spore formation is significantly different from that during fruiting body formation. It was also found that during spore formation, every cell seems to have a potential to form a spore regardless of its age, since smaller cells as well as larger cells separated by sucrose density gradient centrifugation could equally form spores upon the addition of glycerol. Patterns of protein synthesis were almost identical for all the three chemicals. However, the final yield of spores was significantly different depending upon the chemicals used. When phenethyl alcohol was added with glycerol or dimethyl sulfoxide, the final yields were determined by the multiple effect of the two chemicals added. This suggests that although these chemicals are able to induce the gene functions required for spore formation, they may have inhibitory effects on some of the gene functions or the processes of spore formation.