Two women patients with chronic eczematous dermatitis, who also developed extremely severe, persistent photosensitivity during a course of 10 and over 40 years, are presented. Both patients had an atopic history with positive immediate skin reactions. Patch and photopatch tests revealed sensitization to several contact allergens, and in one case also a photocontact allergy. The action spectrum of the photosensitivity was confined to UV-B; it was possible to provoke eczematous skin reactions with doses smaller than 1 mJ/cm2 UV-B. Both patients were successfully treated with PUVA therapy. These case reports demonstrate the difficulty of nosological classification of chronic eczematous photosensitive dermatoses under the traditional terms persistent light reaction, photosensitive eczema, photosensitivity dermatitis, and actinic reticuloid. Chronic actinic dermatitis is defined clinically by chronic dermatitis on skin exposed to sun, histologically by spongiotic dermatitis, and photobiologically by experimental provocation of spongiotic dermatitis with UV-B and often also longer wavelengths in the absence of a photoallergen. Chronic actinic dermatitis should be used as a general term in addition to the more specific terms listed above.