Performance criteria were compiled for the protection of workers during at least 60 minutes of continuous contact while producing, using, or transporting carcinogenic liquids. A simple experimental procedure was developed to measure liquid chemical permeation of protective clothing. The procedure was used to evaluate the barrier properties of polymeric materials against trichloroethylene (79016), epichlorohydrin (106898), coal-tar-creosote (8001589), benzene (71432), 4,4-methylene-bis(2-chloroanaline) (101144) in solvent, ethylenimine (151564), 1,1-dimethylhydrazine (57147), 2-nitropropane (79469), beta-propiolactone (57578), and hexamethylphosphoramide (680319). Breakthrough times, steady state fluxes, and chemical solubilities were measured. The authors conclude that protection could be substantially improved if comprehensive performance profiles were compiled and made available for the design and specification of protective clothing. Permeation testing against specific chemicals to be handled should be performed over the range of anticipated exposure conditions.