1. A cytoplasmic male sterile in peppers has been found, the expression of which is dependent upon a sterile cytoplasm and a nuclear non-restorer gene (ms). 2. Six accessions and six commercial varieties carry the restorer allele, Ms, and two accessions and four commercial varieties carry the nonrestorer, ms. 3. The expression of sterility is affected by modifiers and temperature. Higher temperatures accentuate the sterile expression. 4. Seed set is reduced by approximately one-half in fruit of sterile plants. 5. The significance of temperature influence upon sterility expression is discussed in relation to genic action. 6. The relative infrequency of the ms allele in wild populations and its survival among commercial varieties is discussed.