Abstract Purpose : To investigate the effect of the amount of astigmatism on distance and near vertical heterophoria in adults aged 20~40 years. Methods : Thirty subjects (31.25±10.21 years) were participated, and refraction was performed using I-Profilerplus and a phoropter, and horizontal heterophoria (HH) and vertical heterophoria (VH) teats were conducted at distance and near using a Torrington chart. Results : HH and VH were approximately 0.80 △ (p=0.001) and 0.20 △ (p=0.002) greater at near than at distance, respectively. Spherical refractive errors did not correlate with HH and VH at distance and near. There was no correlation between astigmatism and HH at either distance or near (p=0.141, p=0.318, respectively), but VH at distance and near was significantly correlated with astigmatism (both, p < 0.001), the amount of VH increased with increasing the amount of astigmatism. Conclusion : We found that the amount of astigmatism affected the VH at both distance and near and that the amount of VH increased with increasing astigmatism. These findings suggest that it is important to assess both astigmatism and VH in clinical practice, and that correction of astigmatism may help to reduce symptoms of VH. Key words : Astigmatism, Horizontal heterophoria, Refractive error, Vertical heterophoria