We report the anesthetic technique performed in a 38 year old woman with variegate porphyria who underwent a partial right mastectomy. The patient was diagnosed in 1984 on the basis of the biochemical profile and enzymatic deficit. She presented marked photosensitivity without neurological or systemic symptoms. Among their personal antecedents an uneventful general anesthesia in 1982 was recorded. The patient was premedicated one hour before surgery with 0.25 mg of scopolamine, 5 mg of dihydrobenzperidol (DHB), and 100 micrograms of fentanyl, all of them given by the intramuscular route. At the operating theater the patient received 5 mg of diazepam, 2.5 mg of DHB, and 200 micrograms of fentanyl. Anesthetic induction was done with a bolus of 20 mg of etomidate, 1 mg of atropine, and 60 mg of suxamethonium. Maintenance of the anesthetic level was achieved with 0(2), N2(0) with 0.5 of 1% isoflurane, and 40 mg of atracurium in two doses. Surgery lasted 50 min and pharmacologic reversion of the anesthesia was not required. Urine was collected in a dark recipient 24 hours after surgery in order to measure the following parameters: porphobilinogen, aminolevulinic acid, coproporphyrins and uroporphyrins. We found a significant increase of uroporphyrins at the three sampling times, although this increase was less marked during surgery, probably due to hemodilution. We stress the advantages of inhalation anesthesia in these patients.