This study compared the use of medical resources by recently trained family physicians and general internists. Analyses are based on records of 3,737 adult office encounters with 132 family physicians and 2,250 adult office encounters with 102 general internists. General internists are twice as likely as family physicians to order blood tests, blood counts, chest x-rays, and electrocardiograms for their adult patients. Internists also spend more time with patients, and refer and hospitalize them at slightly higher rates. The different practice styles of general internists and family physicians were evident for adult patients of all ages and for patients with essential benign hypertension. The average per visit charge for diagnostic tests ordered during follow-up visits with hypertensive patients was estimated to be $11.97 for patients seen by general internists and $5.67 for patients seen by family physicians. These findings persisted after controlling for a variety of patient, practice, and physician characteristics.