Tramadol is currently widely administered to patients with chronic pain. We investigated dose, visual analogue scale (VAS), and side effects in cases where tramadol was administered for 3 years or more at our pain clinic center. Tramadol was prescribed in 2,656 cases, and in 50 cases, it was continuously administered for above 3 years (average patient age: 61 years; back pain: 24 cases; upper limb pain: 14 cases; lower extremity pain: 7 cases; post herpetic neuralgia: 4 cases; other: 1 case). Initial VAS score was 70.7 mm; it decreased to an average of 40 mm or less after 3 months. Major side effects included dizziness, somnolence, malaise, nausea, vomiting, and constipation; the incidence of these within the first 3 months was high. There were no serious adverse effects due to the continuous administration of tramadol for above 3 years. Tramadol can be administered in the long term if used carefully while observing the patient.