Background: There is significant demand for dermatologic care, and manpower is limited. Increasing patient encounters stress office processes. Analyses of the effects of schedule manipulation in a high-volume dermatology office have not been described. Objective: The purpose of this article is to study the effects of block versus sequential scheduling on patient waiting times, length of patient encounters, and physician patient-free time in two busy dermatology clinics. Methods: A dermatologist attended at two dermatology clinics, one using sequential patient scheduling and the other, block hourly scheduling. Time of patient arrival, scheduled appointment time, waiting time, time of physician entry into the examining room, face-to-face time with the physician, appointment type, number of same-day cancellations and nonattendance by visit type, length of each clinic, time of clinic closure, and patient-free time were recorded for each clinic and patient encounter. Results: There were no significant differences between patient waiting times at the two clinics. Patients were seen by the physician a mean of 2.6 minutes before their scheduled appointment time using block scheduling of appointments and 6 minutes after their scheduled appointment times with sequential scheduling. Similar times were spent by the physician with the patients at both sites. After adjustment for differing nonattendance rates, block scheduling yielded 330 minutes of additional patient-free time during the course of this study when compared with sequential scheduling. With block scheduling, the clinic finished a mean of 35 minutes earlier than clinics using sequential scheduling. Conclusion: Within the parameters of this study, block scheduling did not significantly affect patient waiting times. Block scheduling created more patient-free time for the physician and clinical staff than did sequential scheduling. Block scheduling increased the quality of the practice environment from the perspective of the physician and the staff. (J Am Acad Dermatol 2000;43:809-13.).