SUMMARY. Thirty patients suffering from sciatica have been treated with purified enzyme concentrate tablets and placebo in a double-blind cross-over trial. In those patients who at first received the proteolytic enzymes considerable decrease in symptoms was observed, while the subsequent administration of placebo tablets did not substantially alter the symptoms. In those patients who received first placebo tablets, little decrease in symptoms was shown until they had also received proteolytic enzyme tablets. Comparison of the incidence of symptoms after one week's treatment between the two groups gave statistiscally significant results.