One hundred nine patients with chronic (3-36 months; mean, 13.4 months) unilateral low-back pain and no signs of sciatica were subjected to facet joint injection, randomized in three therapy groups: cortisone and local anesthetic injected intra-articularly, the same mixture injected pericapsularly, and physiologic sodium hydrochloride injected intra-articularly into two facet joints. To evaluate the results, three outcome variables were formed: work, subjective, and disability outcome. The inappropriate signs (IAS) recorded before injections had the best predictability for a good outcome. The mode of injection or duration of symptoms had no significance as a predictor. It was concluded that the outcome after facet joint injection depends on the patient's biopsychosocial chances of self-facilitated improvement. If abnormal illness behavior and distress are found, it helps to estimate the response for treatment and to choose a realistic method of treatment.