- Objective. Our purpose was to reassess the effectiveness of phenol 4% in aqueous solution for neurolysis in patients with severe chronic nonmalignant pain syndromes who did not achieve adequate pain control (visual analog scale [VAS] ≤3) with conventional pain treatment. Design. Forty-two patients with severe nonmalignant pain persisting for 6 months or longer were followed for more than 6 months after phenol neurolysis in this prospective observational study. All patients had previously received narcotic drugs, with or without nonsteroidal anti-inflammatory agents or adjuvants, without adequate pain relief. An aqueous solution of phenol 4% was used for chemical neurolysis. A fluoroscopically guided technique was used for chemical lumbar sympathectomy, medial branch destruction, and sacroiliac injections. Anatomic-landmarks technique was used for intercostal neurolysis, greater occipital nerve destruction, genitofemoral neuroablation, and paracoccygeal infiltration. Results. Good pain relief (VAS ≤3) was achieved in 35 patients after neurolysis with phenol, and the mean VAS decreased from 8.74 ± 1.08 (range 7–10) before treatment to 1.93 ± 2.41 after treatment (P < 0.0001). The mean VAS for assessment of the quality of pain relief after phenol neurolysis was 8.4 ± 2.39, ranging from 0 (no relief at all) to 10 (complete relief ). No major complications were seen. Conclusion. The use of phenol 4% in aqueous solution is an effective and safe technique for neurolysis. Because of the potential risk of flaccid paralysis, this technique should be used in selected cases, far removed from motor nerves and the spinal cord.