Background and objective: The problems caused by diabetes have direct and indirect impacts on the quality of life of diabetic patients. An increase of these problems means a decrease in a patient's quality of life. This study was conducted to assess the effect of the educational programme based on the precede model in promoting quality of life of patients with type 2 diabetes. Design and methods: This pre- and post-intervention quasi-experimental study was conducted on 78 patients with type 2 diabetes who were referred to a diabetes clinic in Minoodasht, Iran. The educational programme was based on the precede model and patients' educational needs were included in the design. The data were collected using two questionnaires, including The World Health Organization Quality of Life (WHOQOL) questionnaire and the precede model-based educational questionnaire. The subjects were followed for one month after intervention to identify the role of educational intervention them. The data were analyzed by paired sample t-test, variance of analysis test and bivariate correlation test using SPSS version 15. Results: After the intervention, the mean score of quality of life increased from 80.39 plus or minus 11.35 to 81.35 plus or minus 8.31. No significant difference existed in the total score of quality of life after intervention, but there were significant differences in physical health (p less than 0.05), self-evaluation of quality of life by patients (p less than 0.01), and self-assessment of health by patients after educational intervention. In addition, no significant differences were observed between demographic parameters and quality of life, except in the number of children. Conclusion: The educational programme based on the precede model was effective in improving the quality of life of patients with regard to physical health and self-assessment of their health status. (Contains 2 tables.)