Platinum sulfate was administered intragastrically (IG) to adult male Swiss mice in a single dose at the 7 day LD5 or LD25 level. Control groups received 0.25M H2SO4 (pH 0.85) or 0.14M NaCl. Open field behavior (ambulations, rearings) was measured, and tissue/organ Pt levels determined at 4 hr, or 1, 3, or 7 days post administration. At all times, the LD25 depressed ambulations significantly and rearings marginally. It did not effect exploratory ('hole-in-board') behavior. The LD25 resulted in disproportionately high tissue Pt levels relative to the LD5. There were significant inverse correlations between behavior and tissue Pt levels for most tissues, but not for brain. In related experiments, adult male mice were subjected to repeated IG administration of PT(SO4)2 at the LD1 level (one dose every 72 hr for up to 10 doses). Three days after administration of the final dose of each series, open-field and exploratory performance were measured and tissue/organ Pt levels determined. Tissue/organ Pt levels were variable but generally increased with dose number. No Pt was detected in the brain. Activity and explorations were marginally depressed. Only rearings correlated significantly with tissue Pt levels.