In 13 out of 50 patients with eczematous dermatitis with recurrence or aggravation every summer, eczematous reaction was elicited to crude extract of Alternaria, Aspergillus, or Penicillium on intradermal tests. Eczematous reaction was also elicited on patch tests in five of them. Subcutaneous injection or inhalation of crude extract provoked skin lesions. Such eczematous reaction to intradermal test was reproduced with acid-soluble, undialyzable fraction of crude extract, but not with acid-insoluble fraction or ether-soluble fraction. The skin lesions consisted of scattered or grouped, minute papulovesicles in various areas, most frequently in the forearms, dorsa of hands, and neck. Clinical findings differed from those of atopic dermatitis, and the incidence of atopic disease in the past and in family history was low.