- The efficacy and the toxicity pattern of D-penicillamine were studied in patients with rheumatoid disease followed up between April 1975 and March 1979. The population of patients was divided into an elderly group (greater than or equal to 60 years old, mean = 65 years) and a younger group (less than 60 years old, mean = 41 years). Patients with classic or definite rheumatoid disease not responsive to nonsteroidal drugs were eligible. The mean durations of disease prior to D-penicillamine therapy were five years in the elderly and seven years in the younger group. Overall, the mean follow-up time was 11 months. The average dosages of D-penicillamine were 461 mg/day in the elderly and 520 mg/day in the younger patients. Results indicated that D-penicillamine was efficacious in 75 per cent of the elderly during all time periods after three months, and in 75 per cent of the younger patients after three months until at least two years. Prior gold-salt therapy did not influence efficacy. Toxicity was significantly greater in the elderly for overall skin rash (P less than 0.01), severe skin rash (P less than 0.01), and marked abnormalities in the ability to taste (P less than 0.05). The incidence of hematologic toxicity was not increased in the elderly compared with the younger patients. Toxicity in either group was not influenced by prior gold-salt therapy. It is concluded that D-penicillamine was equally efficacious in both elderly and younger groups, and that the toxicity patterns were similar except for increased tendencies toward rashes and taste abnormalities in the elderly.