Irritant contact dermatitis (ICD) is a nonimmunologic reaction elicited by the direct action of a chemical substance on the skin. The pathogenesis of this condition is multifactorial; however, health care workers may be more susceptible to development of lCD. The primary aim of this study was to identify specific factors that predispose to development of hand dermatitis in health care workers. A secondary goal was to determine whether a 24-hour irritant patch test with sodium lauryl sulfate (SLS), sodium hydroxide (NaOH), and benzalkonium chioride (EKe) was predictive of occupational lCD. One hundred health care workers who washed their hands at least 8 times daily completed a questionnaire to identify frequency of handwashing, alcohol-based cleanser use, history of specific medical conditions (including asthma, allergic rhinitis/hay fever, urticaria/hives, atopic dermatitis/ eczema, psoriasis, and easy sunburns) and family history of dermatitis or eczema. Patients were patch tested using SLS (2.5%,5%, and 20%), NaOH (1%, 2.5%, and 5%), and BKC (0.5%, 1%, and 3%) and re-evaluated monthly for 6 months, at which time hands were re-examined for dermatitis and questionnaires were re-administered to assess interval changes. Data was analyzed from 60 subjects who completed the study to date. Sixty-three percent of volunteers developed hand dermatitis. Twenty two percent of patients who reported washing their hands >/=10 times/day developed dermatitis versus 13% of patients who washed their hands < 1 0 times/day (P = .048). Neither use of an alcohol-based cleanser nor use of gloves significantly influenced the development of dermatitis. Other variables assessed in the baseline questionnaire did not significantly alter susceptibility to dermatitis. Regarding the predictive value of patch testing, 73% of patients who reacted to SLS 2.5% and 70% of patients who reacted to SLS 5% (most of whom also reacted at 2.5%) developed dermatitis, whereas non-reacting patients only developed dermatitis at a rate of 42% and 30% (P =.020 and P =.029) respectively. The highest concentration of SLS (20%) resulted in almost uniformly positive reactions and was not useful in predicting susceptibility to hand dermatitis in this cohort. These results indicate that frequent handwashing (>/=10 times/day) may predispose to development of lCD. Furthermore, patch testing with SLS 2.5% and 5% may predict future development of dermatitis.