This study was undertaken to investigate whether levels of anti-Saccharomyces cerevisiae mannan antibodies (ASCMA) in human sera, a marker for several autoimmune diseases, correlate with rheumatoid arthritis (RA). ASCMA-IgA, -IgG and -IgM levels were measured with enzyme linked immunosorbent assays (ELISA) in patients with RA (n = 30) and 152 healthy adult controls. ASCMA-IgA prevalence was significantly higher in RA patients (40%) than in healthy subjects (5.3%). A strong correlation between levels of ASCMA-IgA and CRP (r = 0.695; p < 0.01) and ESR (r = 0.708; p < 0.01) in RA patients was observed. No significant differences in ASCMA-IgG or IgM levels were noted between RA patients and healthy control subjects in the present study. This result differs from previous reports. It remains to be evaluated whether elevated ASCMA-levels are common to all rheumatic disorders.