Patient's appointment is a fixed mutual agreement between patient and any health care giver to obtain the required medical services that suit his/ her health needs.  Appointment delays in outpatient clinics are the most important cause for patients' dissatisfaction due to the complications that might develop during the wait time and consequently affecting their health status. The present study aimed to measure the appointment time from referral from primary health care centers to get the first appointment for patients cared for the most common diseases in the endocrinology outpatient clinic ofAl-Qatif Central Hospital, and study reasons and effect of delayed appointment on patients. It is a cross- sectional descriptive study. The target population was medical records and database of 200 patients, all the working staff, and patients attended the study clinic during the year 2008. Results revealed that 60.5% of the patients had delayed appointment, while 39.5% had no delayed appointment. The acceptable appointment time delay for diabetes mellitus, hypothyroidism and hyperthyroidism were (χ-= 55±8.66, 95±5.00 and 19±4.35 days respectively) in comparison to the current appointment time delay (χ-=118.3±81.0, 113.6±70.4 and 87.9±49.7 days respectively). Most of the patients with delayed appointment were dissatisfied (74.4%) compared to only 67% of those with no delayed appointment. Also, 22.3% of the patients with delayed appointment perceived that their health status was affected to a great extent in comparison to only 10.1% of those with no delayed appointment. Among the reasons mentioned by the working staff for delayed appointment were increased number of “no show" patients, population served by the study hospital, and follow up visits (83.3% each). Accordingly, the present study recommended availability of a center for diagnosis and treatment of diabetes mellitus in addition to the outpatient clinic of the study hospital; developing a system for reminding patients with the date of appointment e.g. SMS, telephone call,…etc; and establishing a prioritizing system for appointments based on emergency of the conditions.