Cytosolic and nuclear fractions of the uterus (shell gland) of the hen's oviduct were found to contain a specific [17alpha-methyl-3H]-methyltrienolone ([3H]R1881; a synthetic androgen) binding component having properties of an androgen receptor; i.e., binding specificity, high affinity, and limited capacity. The value of the equilibrium dissociation constant (Kd) was of the order of 10(-9), and did not differ between laying and nonlaying hens. The maximum binding capacity (Bmax) per gram of tissue of both fractions was greater in laying hens than in nonlaying hens. When 5alpha-dihydrotestosterone was administered exogenously, the Bmax of the cytosolic fraction decreased and that of the nuclear fraction increased without any change in Kd. The specific binding in both fractions was at an increased level from 4 to 11 h before oviposition, suggesting that androgen binding may be related to certain events during an early stage of shell formation in the uterus of laying hens.