This article examines common suppositions about the reasons for female predominance (gender discrepancy, sexual dimorphism) in the autoimmune rheumatic diseases. It suggests that estrogenic hormones are an insufficient explanation. Many illnesses similar to rheumatic diseases are not characterized by sexual dimorphism, nor by evident autoimmunity, yet the populations affected have the same hormonal background. In most other illnesses that are sexually dimorphic, an environmental, behavioral, or genetic reason is present. It is likely that rheumatic illnesses will have similar explanations. For the autoimmune rheumatic diseases, further work in the fields of environmental, genetic, chromosomal, and in utero sex differentiation is indicated.
