Background: Response to diagnostic blocks does not consistently predict the outcome of interventional facet denervation. We investigated the relationship between pain relief by the percutaneous radiofrequency denervation of the lumbar zygapophysial joints with the result of facet joint diagnostic local anesthetic injection in patients with back pain originating from the lumbar zygapophysial joint. Methods: There were 35 patients enrolled, with ranging in age from 25 to 76 years ($52.6{pm}12.7$ years, mean ${pm}$ SD). We studied 7 men (20%) and 28 women (80%). All patients underwent double diagnostic block of $L_{3/4}$, $L_{4/5}$ and $L_5-S_1$ facet joint with 0.5% bupivacaine. The 35 patients fell into the following group. (1) Group A (n = 16): those who felt clear relief (pain free with Likert scale) from the double diagnostic block (2) Group B (n = 19): 11 patients who were always equivocal in their response to the double diagnostic block and 8 patients who were either pain free or equivocal in their response to the double diagnostic block. All 11 patients were done the facet joint denervation. The effect on the pain was evaluated with 4 point Likert scale 1, 6 and 12 weeks after the procedure. We evaluated the relationship between the pain response to diagnostic block and the pain relief with facet joint denervation. Results: Significant correlation was observed between the response to diagnostic block and pain relief with facet denervation (P < 0.05). We found no correlation between the categories of spinal operation and pain response to facet denervation (P value > 0.05). Conclusions: A satisfactory result of lumbar facet joint denervation can be obtained in many patients, especillay in patients whose pain were relieved by the diagnostic double facet joint block. It may be said that facet joint denervation for mechanical low back pain using radiofrequency thermocoagulation is a safe, easy, and repeatable technique.