Two allergen pools of commercial detergent enzymes were prepared as skin test reagents: (1) Carlsberg type, composed of three products containing subtilopeptidase A, and (2) BPN type, composed of two products containing subtilopeptidase B and alpha-amylase. In 100 non-exposed controls a reaction suggesting primary irritancy was found at protein concentrations greater than 1 microng/ml intradermally or 1 mg/ml by prick test. Intradermally at 10 microng/ml weals were accompained by less pronounced flare reactions than observed in specifically sensitized enzyme workers. At 100 micronh/ml the reactions were like strong specific reactions. Galse positive prick test reactions occurred irregularly at 10 mg/ml. In 100 sensitized enzyme workers, reactions were elicited at concentrations from 1-0 to 10(-5) microng/ml intradermally and from 1000 to 1 micron by prick test. Intradermal and prick tests correlated well (r=0-84, P less than 0-001). Ratings of symptom severity upon exposure obtained from questionnaires were significantly correlated with skin test reactivity (P less than 0-01). RAST performed on sera collected simultaneously also correlated significantly with symptom scores. PCA tests in monkeys were less sensitive. Standardized test reagents allow diagnostic skin testing by either intradermal or prick test in B. subtilis enzyme sensitive patients. A clear distinction between primary irritant reactions and true sensitization was made on the basis of the concentration required to elicit a reaction.