To explore related factors of cubital tunnel syndrome caused by cubitus valgus deformity so as to provide theoretical basis for the cl inical treatment. Methods Between June 2002 and September 2008, 40 patients with cubital tunnel syndrome caused by cubitus valgus deformity underwent anterior subcutaneous ulnar transposition. Related factors wasanalysed through logistic regression analysis using scoring standard recommended by Yokohama City University. Results All 40 patients were followed up 27.5 months on average (range, 12-75 months). The duration of cubitus valgus deformity, cubitus valgus deformity angle, and the duration of paraesthesia and muscular atrophy were identified as related factors for ulnar neuropathy and the odds ratios were 1.005 (P=0.045), 9.374 (P=0.000), and 4.358 (P=0.010), respectively. The related prognosis factors were duration of paraesthesia and muscular atrophy, deformity angle, and age at surgery, with odds ratios of 8.489 (P=0.000), 2.802 (P=0.030), and 4.611 (P=0.031), respectively. Conclusion Related factors for ulnar neuropathy are durations of cubitus valgus deformity, cubitus valgus deformity angle, and duration of paraesthesia and muscular atrophy. Related factors for prognosis include age at surgery, cubitus valgus deformity angle, and duration of muscular atrophy. Early anterior subcutaneous ulnar transposition should be performed in patients with cubital tunnel syndrome caused by cubitus valgus deformity