In May 1996, as part of his routine antihepatitis B (hepB) vaccination plan, a 28-year-old HbsAg-negative man, hospital worker, received his first dose (20 microg) of a recombinant vaccine (EngerixB-B, Smith Kline and Beecham, Belgium), administered via deltoid injection. The patient was otherwise healthy and taking no medication. Thirty days after the 2nd booster dose, several pruritic, polygonal, purple, papules appeared on the volar aspect of the patient's wrists. New lesions gradually spread to the arms and trunk (Fig. 1). The clinical diagnosis of lichen planus (LP) was confirmed by histology, which revealed hyperorthokeratosis, hypergranulosis, vacuolar degeneration of the basal layer cells and a dense, band-like lymphocytic infiltrate in the superficial dermis. The disease started to heal after treatment with topical clobetasol propionate 0.05% and sun exposure during the following summer. Five days after the 3rd booster dose, in November 1996, the dermatosis relapsed on the forearms, trunk, and legs. On that occasion, routine laboratory tests, including a complete blood count, blood chemistry and liver function tests, were within normal limits. Screening serologic tests for autoantibodies including antinuclear antibodies, antidouble-stranded DNA, anti-SS-A, anti-SS-B and anti-Sm were all negative. As a result of the inadequate levels of antihepatitis B antibodies, less than 10 IU/l in May 1998, in a high-risk patient who was frequently exposed to blood and its products, an additional booster dose was performed. Three days later a new recurrence of disseminated lichen planus occurred. The patient was successfully treated with prednisone 1 mg/kg/day for 2 weeks. There was no recurrence the following year.