The volatility and lipophilicity by which organic solvents are distinct from other chemicals constitute a characteristic pharmacokinetic feature. They enter a living body by inhalation, preferentially distribute in the adipose tissue, and are eliminated by both expiration and metabolic degradation. This review article is centered on experimental studies conducted by the authors and their co-workers, and it deals with pharmacokinetic principles, partition coefficients in relation to toxicity, significance of metabolism in the development of organic solvent toxicity, and environmental factors that alter the metabolism and toxicity of solvents.