Aims and objectives: The main purpose of this descriptive study was to explore the related factors of adherence among depressive outpatients in Taiwan. Background: Research in Taiwan found that although depressed patients' follow-up rate in outpatient service has increased over the past ten years, about 55% of patients followed up only 3 times or less. Thus ongoing adherence with outpatient treatment by depressive patients in Taiwan is not as high as desired. Understanding the factors that determine why patients did not follow up is important for medical professionals to enhance the treatment of depression. Methods: A total of 181 patients with diagnoses of major depression or dysthymic disorder at two medical centers in northern and southern Taiwan volunteered as study subjects.  Investigators used a cross-sectional research design. Results: The results of this study confirm that Taiwanese patients with depression are adherent with outpatient follow-up treatment 45.9%-50.3% of the time. This is comparable to 47% of patients in a large scale European study, and 30% to 60% of patients predicted in Taiwan. The related factors of adherence were severity of depression (OR= 2.85, 95%CI = 1.28-6.32), knowledge of antidepressant regimen (OR = 2.19, 95%CI=1.15-4.15), and medical professionals-patient interaction (OR=2.23, 95%CI = 1.14- 4.36). Conclusion: This study found that approximately half of depressive patients were adherent with outpatient treatment and follow-up and approximately half were not. Factors resulting in poor adherence include higher severity of depression, less knowledge of antidepressant medication regimen, and less satisfactory medical professionals-patient interaction. To improve Taiwanese patients' adherence, medical professionals should increase patient and family education regarding the illness and related treatment, particularly with more severely depressed patients.  In addition, medical professionals should assess patient/family satisfaction with treatment and respond to areas of dissatisfaction.