Both the precepts and the impact of regional planning for maternity care are often misunderstood. Here, a summary of 8 separate studies in 5 geographic regions describes the reactions of obstetrician-gynecologists to systems of regional planning, as well as their use of the system and the impact of regional planning on their practices. Overall, few physicians acquired new obstetric privileges, and closure of maternity services had limited impact on their practices. Approximately 50% of the physicians referred some patients to level 2 or 3 units, but only 25% actually transferred patients in a given year. The perceptions of a majority of physicians were of improvement in patient services and physician education as a result of regional planning activities. Recommendations are offered for additional needed studies of regional planning efforts.