OBJECTIVE: To compare the clinical and radiographic results of unilateral pedicle screw fixation (UPSF) and bilateral pedicle screw fixation (BPSF) after unilateral transforaminal lumbar interbody fusion (TLIF) for the treatment of lumbar degenerative disc diseases (DDDs). METHODS: A total of 63 patients who underwent UPSF or BPSF combined with unilateral TLIF at L4-L5 or L5-S1 in our hospital between 2014 and 2016 were included in this analysis. The perioperative outcomes and radiographic results were recorded at preoperative and postoperative follow-up. Fusion rates were determined according to the Bridwell-Lenke grading system. Clinical outcomes were evaluated using the visual analog scale, Oswestry Disability Index, and lumbar Japanese Orthopedic Association score. RESULTS: According to the perioperative assessment, the duration of operation, intraoperative and postoperative blood loss, duration of pain medication use, and hospital costs were significantly (P < 0.0001) lower in the UPSF group compared with the BPSF group. After a mean follow-up of 24 months, both the UPSF and BPSF groups showed significantly (P < 0.05) maintained disc height and segmental lordosis of the surgical segment and achieved similar clinical outcomes at the final postoperative follow-up. The impact on the cranial adjacent vertebral level was significantly (P < 0.05) less in the UPSF group than the BPSF group in the short term. CONCLUSIONS: UPSF techniques with TLIF can attain similar clinical efficiency as BPSF techniques in treating single-level low lumbar DDD, but with fewer surgical injuries and at lower cost. BPSF with TLIF likely causes more degeneration at the cranial adjacent segment compared with UPSF techniques. The long-term results require more study.