Summary: Middle‐aged women with a substantiated diagnosis of schizophrenia from Victorian Psychiatric Hospitals were examined for clinical, radiological and serological evidence of rheumatoid arthritis. Clinical or radiological evidence of rheumatoid arthritis was detected in none of the 301 patients studied, where‐as the expected prevalences would be 7.7%; this difference is highly significant (p < 0.001). On the other hand, the prevalence of serologically demonstrable rheumatoid factor in the women with schizophrenia was similar to that in subnormal women in hospital under the same conditions and in women from a normal Australian population. The demonstrable polarity of schizophrenia and clinical rheumatoid arthritis in women might be explained either on a genetic basis or through the “protective” effects of one disease, schizophrenia, on the occurrence of the other, rheumatoid arthritis.