Eight adult patients with hereditary hepatic porphyria have been found among five unrelated Chinese families in Taiwan. Five patients in three families were considered to have porphyria variegata; included were a mother and her son and daughter in one family and one male and one female subject in two other families. The remaining three patients, including two sisters in one family and one female in another family, were diagnosed as cases of acute intermittent porphyria. Sixteen latent cases were found among other members of the five families. Clinical and biochemical findings in the eight patients were in general agreement with those reported in porphyria patients in other ethnic groups. Mental symptoms were commonly found in the latent as well as in the overt cases during both remission and acute stages of the disease. d-penicillamine therapy was tried for a short period of time in one patient with porphyria variegata with encouraging clinical and biochemical signs of improvement.