The immunohistochemical expression of the androgen receptor (AR) was investigated in the ovarian atretic follicles and corpora lutea (CL) of pregnant pigs and rats, as well as in porcine uteri and fetuses. Follicular atresia involved either abnormal persistence or depletion of AR in various follicular compartments. Porcine and rat CL expressed nuclear AR. However, in the porcine CL, starting from day 70 of pregnancy, mainly cytoplasmic staining was observed, with exclusively cytoplasmic expression found on day 90. In the CL of pregnant rats, differences in AR distribution within the same CL were observed and decreasing AR expression during luteal regression was found. AR mRNA and protein expression in the porcine uterus depended on the uterine compartment and the day of pregnancy. AR-positive were also testes, ovaries, uteri, kidneys and lungs of fetuses.