We studied British general practitioners' use of ambulatory resources to determine whether the quantities of different resources used were related to each other, and whether these quantities were associated with their personal characteristics. Rates of laboratory requests, referrals for specialty opinion, prescriptions, and visits per patient per year were examined for 21 physicians in seven practices over one year. Physicians who more frequently saw their patients referred and prescribed for them more often and ordered more tests, once the number of years they had practiced was taken into account. Doctors who ordered more tests referred their patients more frequently, regardless of how often they saw them. Doctors longer in practice saw and prescribed for their patients more frequently. Resource use was not related to other personal characteristics we studied. Greater frequency of patient-physician contact appears to increase costs not only through use of more professional time but also through greater use of other ambulatory resources. Attention to the use of only one type of resource may result in a distorted picture of how physicians care for their patients and the costs that such care incurs.