Forty cases of chemical lumbar sympathectomy are presented. A 7.5% solution of phenol in meglumine iothianate was injected under local anaesthesia and abdominal radiography performed. Skin temperature changes in the legs were compared with the radiological appearances and clinical results. Six injections were performed on cadavers before autopsy using a solution of methylene blue and meglumine iothianate in order to correlate the radiological appearance with the exact site of the injection. In 36 patients 32 injections were correctly sited at the first attempt. The 4 patients in whom technical failure occurred were successfully reinjected at the second attempt. Four correctly sited injections failed to produce a response and were not repeated.