Purpose: Organized as descriptive research, the present study aimed to investigate the internalized stigma, self-esteem and perceived social support levels in schizophrenia and bipolar disorder patients who were followed at a psychiatry outpatient clinic. Materials and Methods: The study was conducted with 162 schizophrenia and 200 bipolar disorder patients who applied for treatment at two state hospitals and one university hospital. Data for the study were collected using patient information forms, the Internalized Stigma of Mental Illness Scale (ISMIS), the Rosenberg Self-Esteem Scale (RSES) and the Multidimensional Scale of Perceived Social Support (MSPSS). Results: The ISMIS mean scores showed statistically significant differences based on the diagnoses of the patients, awareness of the diagnosis, suicide attempts and regular psychiatric care among the patients. The ISMIS mean scores of patients with the diagnosis of schizophrenia were significantly higher than those of the bipolar disorder patients. The ISMIS mean scores of the patients who did not know their diagnoses, who attempted suicide and who did not attend follow-ups regularly were higher. There was a positive correlation between the ISMIS and RSES scores of the patients. In contrast, there was a negative correlation between the ISMIS and MSPSS scores. Conclusion: There is a relationship between low self-esteem and low social support perceived by patients and internalized stigmatization. It is therefore important to plan and conduct initiatives to increase patients' self-esteem and social support.