There is evidence that chronic pain disorders such as Myofascial Pain Syndrome (MPS), resulting from repeated biomechanical stress caused by ergonomic hazards. e.g. trauma and overuse of the muscles, often occur in agricultural workers. Hypothetically, the neuropathic character of MPS makes the disease unresponsive to the typical analgesics. Accordingly, in this study three trials of treatment in patients with MPS were performed and compared. The first trial (I) was based on rehabilitation, while the second (II) was based on treatment with sertraline, an antidepressive, serotoninergic drug. For third trial (III), rehabilitation plus the above-mentioned administration of sertraline, were applied. Altogether, 49 patients were recruited to the trials. Control group consisted of 23 persons. Response to the treatment was assessed according to the criteria of neuropsychological tests MADRS and BDI. The MPS syndrome was found to be relatively common in Polish farmers and formed 12.7% of all chronic pain syndromes diagnosed in the Institute of Agricultural Medicine during 18 months. All the patients with MPS showed mood disorders in the baseline assessment by the neuropsychological tests. Patients from groups I, II, and III declared improvement after two months of the treatment (77%, 80% and 93% respectively). In the neuropsychological tests, only patients treated with rehabilitation and sertraline (group III) showed statistically significant improvement in comparison with baseline assessment both after one month and after two months of the observation. Thus, rehabilitation and serotoninergic system modification might be a good solution in the management of MPS.