Hospital- based surveys and the few population studies (one in West Africa and two in South Africa) on the pattern of rheumatoid arthritis in black African population groups have created the impression that the disease is rare here and generally runs a milder course. A noteworthy exception was found to be the urbanized population of Soweto, where both the prevalence and the severity of the disease among the females resembled the usual pattern observed in the industrialized countries. Since experience in the outpatient department of Scott Hospital, a mission hospital in Lesotho, seemed to point to a different picture of the disease in this country, it was decided to conduct a prospective hospital study to verify this impression