We have analyzed the entire nucleotide sequences of complementary DNAs of the androgen receptor gene in two siblings (patients 8044 and 8047) with complete androgen insensitivity. Plasma testosterone was in the normal male range, however, androgen binding capacity was undetectable as measured in skin fibroblasts in both patients. 5alpha-reductase activity was normal in both cases confirming that this enzyme is not involved in the mechanism of androgen insensitivity. Northern blot analysis indicated that mRNA of the AR was normal in size. In addition, no mutation was found in the entire nucleotide sequences of complementary DNAs of the androgen receptor gene. Together, our results reveal an unusual insight into the molecular basis of androgen resistance, and the molecular heterogeneity in this clinical spectrum.