During our first year of routine testing with Compositae allergens and extracts, contact allergy to Compositae was frequently found in eczema patients (4.5%), especially in middle-aged or elderly persons. Based on clinical patterns, patch test reactions and the long-term course of the disease, 4 groups of patients were recognized: (a) a small group with localized eczema; (b) another with classic Compositae dermatitis of exposed skin; (c) a 3rd group, the largest, with localized eczema that suddenly one summer turned into a widespread dermatitis; (d) a 4th group with a vesicular hand eczema and more-or-less widespread dermatitis with seasonal variation from the beginning. 65% of the patients had vesicular hand eczema at some time, partly reflecting the frequency of atopy (25%) and metal allergy (44%). 75% of the patients had contact allergy to > or = 1 compounds besides Compositae. Thus, Compositae allergy may be primary, e.g., in young patients with occupational plant contact, or secondary to other contact allergies, perhaps as a result of increased individual susceptibility. The clinical patterns in the latter patients were most often a widespread dermatitis with summer exacerbation. The variability in the clinical picture makes routine patch testing with Compositae allergens recommendable.