We experienced 29 cases of tentative photo allergic disorders from April 2000 to March 2002. For those 29 patients, photopatch tests have been done to explore possible causative photoallergens. We performed photopatch tests with photo-related allergens and possible causative products that the patients brought to us. After applications for 48hrs, one test site was irradiated with half of MRD or 6.0 J/cm$^2$ of UVA. Readings were evaluated according to the reading criteria of the ICDRG. Photoallergens were suggested in 20 cases (69.0%). Among them, we could find out the causative products in 7 cases (24.1%). Photopatch tests, performed by an appropriate method, are useful in some cases not only for diagnosis of photocontact dermatitis but also diagnosis of systemic photoallergic disorders.