The purpose of this study was to determine if the etiology of Wasting Marmoset Syndrome (WMS) is related to zinc deficiency. The clinical symptoms of zinc deficiency and WMS are very similar. It was determined that S. mystax exhibiting signs of WMS were zinc deficient. The study involved feeding two diets to several wasting S. mystax, one diet was supplemented with zinc carbonate and the other was not. Serum zinc concentrations and blood chemistries were sampled on a regular basis. Tissues were taken from dead tamarins for zinc analysis. The S. mystax is an invaluable laboratory animal model for immunological research. However, in captivity, many of these tamarins are unable to breed and eventually die due to WMS. The fact that S. mystax are zinc deficient may provide an answer to the etiology of WMS.