The exact significance of a reported androgen deficiency in women with lupus has not yet been determined. The authors decided to study plasma androgen concentrations not only in lupus, but also in other auto-immune diseases as well as non-auto -immune diseases. 43 patients (rheumatoid arthritis (RA): 10; systemic lupus erythematosus (SLE): 11; multiple sclerosis (MS): 11; patients without auto-immune disease: 11) were compared to 13 normal women. The age and the hormone concentrations of these different groups were compared by analysis of variance and by the Kruskal-Wallis test. A statistically significant reduction in androgen levels was only detected in the women with lupus. It therefore appears that the androgen deficiency is not a non-specific consequence of any disease, that it does not represent a predisposing factor for auto-immune disease in general, but that it is specific for lupus.