The measurement of rheumatoid factors is of limited value in West Africa due to the low rheumatoid factor seroprevalence among patients with rheumatoid arthritis and the increased seroprevalence among healthy individuals and those with infectious diseases in the region. Using ELISA methods, we have been able to increase the specificity of rheumatoid factor measurement although the sensitivity of this test remains low. Furthermore, among the infectious diseases studied, there was no preferential binding of rheumatoid factors to the Fab gamma portion of immunoglobulin over the Fc gamma portion.