Contact reactions to procaine penicillin G are to be expected inasmuch as both procaine and penicillin are fairly common sensitizers. To focus attention on this possibility, the following case of contact dermatitis is reported. A. R., a white man aged 43, was a research chemist for a pharmaceutical concern. Two weeks before I saw him on April 9, 1948, he acquired a dermatitis over his fingers, face and neck. There was intense itching. He had never had a previous skin problem. He was suspicious of procaine penicillin G inasmuch as he had begun working with this preparation a few days before his eruption began. Also, he had had considerable improvement in his condition during several days when he was away from the substance. He had previously worked with both procaine and penicillin with no ill effects. He presented a patchy, erythematous eruption about the neck and over the face. It