Thirty-eight urban volunteers from the Lincoln and Omaha, Nebraska areas were monitored for carbaryl exposure during the summer of 1979. All volunteers were involved in the application of carbaryl incidental to their employment or leisure activities. The investigators made no attempt to affect the method of carbaryl application. The mean rates of carbaryl exposure were 3.85 and 0.26 microgram cm-2 hr-1, respectively, for the outside of the clothing and the skin beneath the clothing; clothing apparently provided an effective barrier to carbaryl penetration. The rate of carbaryl exposure to the hands of applicators was 2.36 and 24.96 micrograms cm-21 hr-1, respectively, for applicators with and without gloves. The maximum dermal exposure recorded in this study was 2.86 mg kg-1 hr-1 which is significantly less than the stimated dermal LD50 value for carbaryl (4000 mg kg-1). The maximum air concentration of carbaryl was 0.28 microgram L-1. Only a small mean decrease was found in the applicators serum (-1.01%) or erythrocyte (-1.39%) acetylcholinesterase activity. Although some applicators had decreases in either serum or erythrocyte acetylcholinesterase activity greater than 20%, an equal number had increases of the same magnitude. The mean total carbaryl exposure to the applicators, expressed as a percent of toxic dose per hr, was 0.01%, with a maximum estimated exposure of 0.08%.