AIM:To study the association between dominant eye and anisometropia, and get a deeper understanding of the cause of anisometropia. METHODS:Four hundred eighty-six cases (972 eyes) with anisometropia were divided into hyperopic, myopic and mixed nature groups according to the different properties of anisometropia. Diopter was accessed by Computer Optometry after cycloplegic refraction. Ocular dominance was determined using the simplified hole-in-card test. The relationship was analyzed between the dominant eye and the higher diopter eye in each group. RESULTS:There was obvious relationship between the dominant eye and the lower diopter(Z=-4.116,P<0.01) in the hyperopic anisometropia group. Thus the diopter of the non-dominant eye was higher than the dominant eye. There was no relationship between the dominant eye and the lower diopter (Z=-0.304，P>0.05) in the myopic anisometropia group. There was obvious relationship between the dominant eye and the eye of myopia (Z=-3.645，P<0.01) in the mixed group. CONCLUSION:The dominant eye should form prior to the occurrence of anisometropia. But anisometropia may cause the dominant eye to change.