The present study aims to investigate the mental state changes in patients with lumbar intervertebral disc damage after rehabilitation program using a self-administered questionnaire IRES-3. The study was conducted in the Specialized Hospitals for Rehabilitation – National Complex EAD, branches Hissar and Banite, Bulgaria. It included 124 patients – 34 men and 90 women, aged from 35 to 85 years. The questionnaire IRES-3, validated by the authors for the Bulgarian population, was used for measurement of the subjective evaluation of the rehabilitation effect. Measurements were performed at the beginning, end and three months after rehabilitation (RH). The subjective evaluation of the patients’ mental state included the following scales: depression, fear, exhaustion of vitality, self-confidence and symptom: cognitive functioning. We found a statistically significant improvement of the scores three months after rehabilitation compared to the beginning of rehabilitation for all scales. The only exceptions are the scales exhaustion of vitality and symptom: cognitive functioning. We found a statistically significant improvement of the self-rated mental state after performed rehabilitation in patients with chronic diseases.