Background: Radiofrequency neurotomy (RFN) is an effective treatment option for patients with severe sacroiliac joint (SIJ) pain. Aims: We evaluated the 12-month clinical outcomes between patients (n=93) having RFN of the lateral branches of S1-S3 compared to patients (n=89) undergoing the same procedure augmented with RFN of the L4 medial branch and L5 dorsal ramus. Methods: This was a retrospective chart review. Following diagnostic intra-articular anesthetic injections and multi-site multi-depth lateral branch nerve blocks to establish SIJ pain, patients underwent bipolar ablation of the S1-S3 lateral branches using the Nimbus multitined electrode. The second group of patients underwent supplementary monopolar RFN of the L4 medial branch and the L5 dorsal ramus. Pain severity and global Pain Disability Quality of Life Questionnaire-Spine (PDQQ-S) scores were obtained prior to RFN and at 12 months. Results: There were 61% and 59% average 12-month improvements in SIJ-related pain severity and global PDQQ-S scores, respectively, in the overall study group (P<0.001 for both comparisons). Efficacy was moderately better for patients with augmented ablation that captured the L4 medial branch/L5 dorsal ramus. For example, 12-month average pain reduction was 54% and 66%, and PDQQ-S improvement was 56% and 62% for patients treated with S1-S3 lateral branch RFN and the augmented RFN procedure, respectively. The percentage of patients exhibiting ≥ 50% improvement in pain severity at 12-months was 73% (68 of 93) and 88% (78 of 89) (P=0.016) for the same study groups. Conclusion: RFN of the S1-S3 sacral lateral branches using an anatomically accurate bipolar strip lesion technique produced a sufficient lesion topography to provide highly significant pain reduction and improvement in PDQQ-S at 12-months follow-up. Including the L4 medial branch and L5 dorsal ramus in the RFN treatment protocol may offer more complete denervation of all afferent pain pathways and provide additional clinical benefit.