OBJECTIVE: To evaluate the effects of perceived self-efficacy training program in type-2 diabetes. METHODS: A total of 54 diabetic patients were randomized to the intervention or control group at primary care unit, Samutsakhon Hospital, Thailand. Patients in the intervention group entered perceived self-efficacy training program, those in the control group did not. The patients' perceived self-efficacy, self-care behaviors, and knowledge in diabetes were assessed using questionnaires at the beginning and at three months after entering the training program. RESULTS: There were 27 patients in each group. No significant differences between the two groups were found at the beginning of the study with respect to perceived self-efficacy, self-care behaviors, and knowledge in diabetes. After the program, self-care behaviors of patients in the intervention group were better than those in the control group (56.00 ± 5.54 points VS 50.85 ± 5.99 points, P = 0.002). Perceived self-efficacy and knowledge in diabetes in the intervention group also improved, but not significantly so, compared to the control group. CONCLUSIONS: Although the perceived self-efficacy training program does not affect the perceived self-efficacy of type-2 diabetes, it significantly improves their self-care behaviors. It has yet to be seen as to whether these behaviors are sustainable and for how long.