Hydroa vacciniform is a rare recurrent photosensitive skin condition in which deep-seated vesicles appear on sun-exposed areas and heal leaving a depressed scar. Two cases are reported, with particular emphasis on phototesting investigations. Results of blood and urine porphyrin studies were normal and no systemic abnormalities were noted. Phototesting may be viewed as an important diagnostic aid, since the induction of lesions, clinically identical to hydroa vacciniform can occur following sequential exposure to UV-A, as was the case in one of our patients.