Previous studies reported that respiratory feedback (RFB) aids in alleviating chronic pain. However, to date, this adjunct treatment has not been rigorously tested against non-contingent (placebo) feedback. Forty-two patients with chronic low back pain were randomized to either RFB or non-contingent RFB. Both groups performed a daily 30-min home training for 15 consecutive days. A respiratory associated relaxation index (RI) was measured. Pain levels and a somatosensory profile were assessed before and after intervention. Additionally, pain levels were assessed 3 months after the end of intervention. Secondary outcome parameters included daily functioning, psychopathology, and suggestibility. T-tests showed higher and significant pain reductions for RFB, compared to non-contingent RFB. Between-group comparisons reached no significance. However, changes were more pronounced in the RFB condition, which was also true for the course of the RI and the psychopathological scores. This is the first study using a non-contingent respiratory placebo feedback in a randomized, controlled design. Within this design previous positive findings of symptom reductions in patients treated with RFB could partially replicated. Nonetheless, tendencies suggest that contingent feedback patients compared to placebo patients profit more from RFB in the long run regarding reduction of chronic pain and psychological distress.