The trypsin-inhibitory-capacity was measured with a gelatine-film-technique after JAMES et al, in 520 persons suffering from complaints of upper and/or lower airways in connection with exposure to respirable allergens and/or irritants. As a control group 214 blood donors were examined. After determination of normal range, relations to age, sex, smoking habits, ventilatory parameters, bronchial reactivity, sedimentation rate of blood cells, alpha1-globuline and IgE were examined. In workers exposed to enzymes mean values to trypsin-inhibitory-capacity were found to be in normal range. Determination of trypsin-inhibitory-capacity is proposed to be used in examinations of workers who are to be exposed to enzymes.