The increasing problem of environmental contamination by chemicals has suggested the potential usefulness of a cell bioassay system permitting the rapid screening of the toxicological properties of chemicals under standardized conditions. Using quantitative methods of mammalian cell culture, a series of preliminary investigations were carried out on a selected group of toxic chemicals. These studies demonstrated that the toxicity of all chemicals investigated could be determined with sufficient precision and sensitivity to establish a unique relative toxicity for each chemical and to permit an analysis of the kinetics of toxic action. In this study, bovine ovary cells plated into petri dishes were exposed to varying concentrations of rotenone, cadmium, zinc, copper, chromium, and NTA continuously for 7-9 days. The relative plating efficiency was determined and titration curves were constructed. In the kinetic phase of this study, attached cells were exposed to single concentrations of the toxic chemical for varying time intervals and the relative plating efficiency followed as a function of exposure time. The log of the surviving cell fraction was plotted against exposure time giving classical survival curves.