AIM:To study the clinical characteristics of dissociated vertical deviation with inferior oblique muscles hyperfunction,and analyze clinical effects on the surgical treatment with superior inferior oblique muscles anterior transposition. METHODS:Forty-eight patients of dissociated vertical deviation with inferior oblique hyperfunction were treated by superior inferior oblique muscles anterior transposition.Breaking and fixing inferior oblique muscles at the temporal rectus inferior 1mm and under rectus inferior 1mm. Following-up was from 2 weeks to 12 months. RESULTS:The correction in the vertical strabismus angle had no singnificant difference between small degree group with moderate degree group.However,the correction in the vertical strabismus angle had a singnificant difference between small and moderate degree group with large degree group. CONCLUSION:The surgical treatment with superior inferior oblique muscles anterior transposition is safe and effective.