Objectives: The study aims to assess selected factors contributing to the long-term effects of the conservative treatment of carpal tunnel syndrome (CTS). Material and Methods: Forty-nine individuals diagnosed with CTS were enrolled in the study. The symptoms resulted from occupational hand overuse in 37 patients. The assessment involved 78 hands before the therapy (study 1) and 1 year after the end of the therapy (study 2). The clinical symptoms assessed included: pain, numbness, tingling, morning stiffness, vegetative disorders and difficulties in activities of daily living (ADL). The range of motion (ROM) in the hand joints and the pressure generated during the cylindrical grip were measured. Phalen’s tests, an electrodiagnostic test and a 2-point discrimination study were performed. Results: A significant reduction of symptoms and improvement in tested parameters were found in study 2. The largest ROM in the hand, the lowest level of pain and the largest reduction in the frequency of daytime tingling were found in the oldest patients in study 2. In subjects with better initial electrodiagnostic test results, a significant reduction in daytime numbness and daytime tingling was obtained. In individuals previously subjected to conservative therapy, a significant improvement in the ROM of the hand and a better quality of sensation were noted in study 2. A higher level of pain, a lower reduction in the frequency of daytime tingling, and a smaller improvement in ADL capacity were noted in individuals who overused their hands at work after the therapy. Conclusions: The effects of conservative CTS treatment after 1 year, expressed as the reduction of subjective symptoms, were independent of the patient’s age. A worse initial electrodiagnostic test result is a predictor of less favorable therapy results. Hand overuse during occupational activity may negatively affect the effects of conservative treatment in individuals with CTS. A change in the nature of occupational activity positively influenced the long-term maintenance of the effects of conservative treatment. Int J Occup Med Environ Health. 2019;32(2):197–215