The prevalence of eosinophilia in 82 rheumatoid arthritis patients receiving gold sodium thiomalate (GSTM) and 30 patients receiving auranofin (AF) was determined in a retrospective study. Eosinophilia occurred in 21% taking GSTM and in 13% on AF. The simultaneous occurrence of toxicity and eosinophilia occurred in 14% receiving GSTM and in 10% receiving AF. In contrast, eosinophilia only occurred in 24% of those with suspected toxicity receiving GSTM and in 30% of those with suspected toxicity receiving AF. The value of eosinophilia as a marker of toxicity is discussed.