Residual chemicals can leach from medical devices that contact biological membranes. In repeat studies, when subcutaneously implanted into mice, one brand (Brand A) of latex surgical drain consistently produced acute toxic reactions resulting in mortality within 12 h. This was not found with other brands tested. This abstract describes the methodological approach used to isolate and identify the toxic agent leached from Brand A. Experiments were designed to selectively leach/ partition the toxic substance from the surgical drain into latex compatible solvents, characterize the washes by GC/MS, and assess the toxicity of the washed drains. A non-toxic drain (Brand B) was used as a control. Methanol and acidic water, but not saline or alkaline water wash resulted in loss of toxicity from Brand A. This suggested that the toxic agent had some solubility in methanol and was probably a basic compound. Zinc diethyl dithiocarbamate (ZDEC) was the only compound found in both the methanol and acidic water Brand A washes, but not in the alkaline water wash nor any of the Brand B washes. Subcutaneous administration of ZDEC produced the same spectrum of toxic reactions as Brand A. The general approach of selective leaching/partitioning coupled to chemical analysis and toxicological assessment provides a useful tool for the identification of potentially hazardous residues in medical device materials.