IMPORTANCE Cubital tunnel syndrome is the second most common compressive neuropathy, affecting 6% of the population. Numerous different operations are performed globally to treat it; however, prior conventional (pairwise) meta-analyses have been unable to determine which procedure is associated with the best outcomes and fewest complications. OBJECTIVE To evaluate which operation for cubital tunnel syndrome is associated with the greatest likelihood of symptomatic cure. DATA SOURCES PubMed, EMBASE, and CENTRAL were searched from database inception to March 2, 2019, with no restrictions on the setting or design of studies. STUDY SELECTION Experimental and observational studies directly comparing the outcomes of at least 2 surgical treatments for adults with primary cubital tunnel syndrome were included. Case reports were excluded, and when comparative studies had subgroups with 1 participant, the singleparticipant subgroup was excluded. The treatments had to be in situ decompression with or without medial epicondylectomy or an anterior subcutaneous, subfascial, intramuscular, or submuscular transposition. The access could be open, minimally invasive, or endoscopic. The comparator could be sham surgery or any operation mentioned earlier. DATA EXTRACTION AND SYNTHESIS Data were extracted by 2 independent reviewers, following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline and the PRISMA Network Meta-analysis extension statement. Network meta-analysis was used to estimate the relative efficacy and safety associated with interventions using relative risks. Surgical techniques were ranked by their probability of being the best (P score) and interpreted in terms of their clinical impact. MAIN OUTCOMES AND MEASURES The primary outcome was response to treatment (ie, symptomatic improvement). The secondary outcomes were perioperative complications, reoperation, and recurrence. RESULTS A total of 30 studies of 2894 limbs undergoing 8 different operations were included. Across the studies, 56% of participants were men, the mean (SD) age was 48 (8) years, and patients had symptoms for a mean (SD) of 15 (7) months. Overall, 87% (95% CI, 92%-91%) of patients improved with surgery; all forms of in situ decompression were more effective than any type of transposition procedure; for example, open in situ decompression with epicondylectomy was (continued) Key Points Question For adults with primary cubital tunnel syndrome, which operation is associated with the best chance of symptomatic cure and lowest risk of complications? Findings This network meta-analysis included 30 studies comparing 8 different operations in 2894 limbs. It found that 87% of patients improve with surgery and that open in situ decompression (with or without a medial epicondylectomy) was associated with the greatest response to treatment and lowest complication risk. Meaning The findings of this study suggest that for adults with primary cubital tunnel syndrome, the most beneficial operation appears to be ope...