The use of various gases for the sterilization of nondisposable and disposable plastic medical devices has become firmly established in the past decade and a half. However, the subject of sterilant residues remaining in plastic devices following an ethylene oxide gas sterilization has only recently been investigated. This study correlates ethylene oxide residues as determined by gas chromatography to the ability of these residues in polyolefins to elicit toxicological responses in several biological systems. A comparison of the results from a quantitative hemolysis test, rabbit intramuscular implantations with subsequent pathological investigation, cell culture responses, a series of fish tests, and intradermal irritation studies, to the ethylene oxide desorption data, revealed that within 24 hr. after sterilization, no significant toxicities were produced by ethylene oxide-sterilized polyolefins. The concentrations of the gas had decreased from a high of 3.20 mg./g. of plastic to as little as 0.20 mg./g. of plastic after aeration at room temperature for 24 hr. Keyphrases 0 Plastics, sterilized-ethylene oxide (EtO) residual a Ethylene oxide residual, plastics-toxicity 0 Guppy-toxicity determination, EtO residual 0 Cell cultures-toxicity determination, EtO residual C. Intradermal irritation-