A tissue culture cytotoxicity study was conducted to evaluate the biocompatibility of polydimethylsiloxane fluid with human cells. The negative control was Silastic 372; while Latex catheter served as the positive control. Extracts of the test and control substances were prepared by heating samples in either cottonseed oil, 0.9 percent sodium chloride, or MEM tissue culture media. Each test material and each extract were placed in direct contact with a confluent monolayer of human embryonic lung cells and incubated for 24 hours. After incubation, the cultures were examined microscopically at 10x magnification and compared to positive and negative controls to evaluate cytotoxicity. No cytopathic effects were reported for polydimethylsiloxane fluid or its extracts.