We report a successful treatment with lamotrigine of a patient with hereditary coproporphyria presenting with affective and psychotic symptoms. M.F., a 38-year-old, single woman was admitted to an acute psychiatric ward because of suddenly emerging psychosis. Ms F's hereditary coproporphyria was diagnosed 9 years before the current admission. While on treatment with olanzapine (20mg/day) the psychotic symptoms have gradually disappeared. In view of her significant mood fluctuations predominantly with depressed phases, lamotrigine was started and titrated up to 125 mg/day. Ms F's mood gradually became euthymic, suicidal ideations and anxiety disappeared. At 5-month follow-up, while still on lamotrigine, her porphyria was asymptomatic. To the best of our knowledge, this is the first report about the safe administration of lamotrigine in hereditary coproporphyria. Lamotrigine did not trigger an acute porphyric attack as confirmed by clinical and laboratory findings.