We analysed the functional outcome (Oswestry Disability Index) after technically and radiologically successful lumbar fusion in 39 non-compensation seeking patients with chronic low back pain, who had a High Intensity Zone (HIZ) – positive MRI and subsequently underwent discography. The average follow-up was 33 months. The HIZ-positive, discogrampositive group was the only one with statistically significant improvement. The HIZ-positive, discogram-negative group had the worst outcome. Relying only on the HIZ fails to identify the group of patients who would have had negative discography at the same levels. Therefore the presence of HIZ alone should not dictate treatment plan without discography confirmation.