Objective To observe the characteristics of morphosis parameter of the optic disc of physiologic large cup. Methods 100 eyes with physiologic large cup and 74 eyes with normal cup were examined by Heidelberg Retina Tomograph (HRT ). The differences of morphosis parameters between two groups were analyzed comparatively on disc area (DA), cup volume (CV), cup/disc area ratio (C/DR), rim area (RA), cup volume (CV), rim volume (RV), mean cup depth (MeCD), maximum cup depth (MxCD), cup shape measure (CSM), height variation contour (HVC), mean retinal nerve fiber layer thickness (mRNFLt), and retinal nerve fiber layer cross-section area (RNFLcsa). The characteristics of the inferior, superior, nasal, and temporal quadrants of the physiologic large cups were analyzed. Results DA, CA, C/DR, CV, MeCD, CSM （P=0.00, respectively）and MxCD （P=0.04）were significantly larger in eyes with physiologic large cup than in eyes with normal cup. RA, RV, HVC, mRNFLt, RNFLcsa （P=0.00, respectively) were significantly smaller in eyes with physiologic large cup than in eyes with normal cup. The temporal quadrant of RV of the physiologic large cup is the narrowest. RNFLcsa decreased as the fol lowing order: superior, inferior, nasal, and temporal（P＜0.05）. Conclusions Mo rphosis parameter of the optic discs of physiologic large cup has its own repres entation on characteristics. Compared to normal cups, physiologic large cups had larger discs but smaller mRNFLt. The nasal quadrant of DA was larger than the i nferior quadrant. （Chin J Ocul Fundus Dis，2008，24：213-216）
