Background: When faced with questions about patient care, family physicians usually turn to books in their personal libraries for the answers. The resources in these libraries have not been adequately characterized.

Methods: We recorded the titles of all medical books in the personal libraries of 103 randomly selected family physicians in eastern Iowa. We also noted all clinical information that was posted on walls, bulletin boards, refrigerators, and so forth. Participants were asked to describe their use of other resources such as computers, MEDLINE, reprint files, and "peripheral brains" (personal notebooks of clinical information). For each physician, we recorded how often the resources were used to answer clinical questions during 2 half-day observation periods.

Results: The 103 participants owned a total of 5794 medical books, with 2836 different titles. Each physician kept an average of 56 books in the office. Prescribing references (especially the Physicians' Desk Reference) were most common (owned by 100% of the participants), followed by books on general internal medicine (99%), adult infectious disease (89%), and general pediatrics (83%). Books used to answer clinical questions were more likely to be up to date (copyright date within 5 years) than unused books (74% vs 27%, P <.001). Items posted on walls included drug dosage charts and pediatric immunization schedules. Only 26% of the physicians had computers in their offices.

Conclusions: Drug-prescribing textbooks were the most common type of book in family physicians' offices, followed by books on general internal medicine and adult infectious diseases. Although many books were relatively old, those used to answer clinical questions were generally current.