Water permeability constants (Kp) were determined with skin from human cadavers. No difference was seen in Kp values from unfrozen skin or from skin frozen for a few days. Human skin could usually be stored at -20 °C for up to a year with no change in water permeability, but in some cases apparent deterioration of the barrier was observed. A rapid procedure was developed for checking barrier integrity of skin in diffusion cells before a penetration study. The percent of the water dose absorbed after 20-min contact with skin correlated with water Kp values. Changes in water permeation through human skin agreed with changes in the absorption of seven test compounds of varying solubility properties (acetylsalicylic acid, benzo(a)pyrene, cortisone, DDT, nicotinic acid, propylene glycol, and testosterone). Water permeation is therefore considered to be a good indicator of potential changes in the barrier integrity of human skin. No correlation was observed in Kp values and other characteristics of the donor skin samples such as age, sex, race, and length of time before skin harvest.