Temperature-induced effects on the synthesis of murine testicular proteins were investigated by one- and two-dimensional SDS polyacrylamide gel electrophoresis. Newly synthesized proteins were monitored by incorporation of 35S-methionine and autoradiography. Three heat shock responsive proteins, which are differently affected by elevated temperatures, are described. These proteins represent special examples for how testicular cells respond to environmental stress. One of these proteins, HSl36, is synthesized and secreted at 38 degrees C, whereas at lower, scrotal temperatures it is not detectable. HSlD74 protein is synthesized at elevated temperatures, but only in prepuberal testis, not in adult. Synthesis of the third example, HSR28, is decreased within the seminiferous tubules, but only in those regions which bear cell associations of the elongation stage. These results indicate that the use of DNA probes of the 'heat shock'-gene family might not be sufficient to describe the molecular reasons for impaired spermatogenesis following hyperthermia.