PURPOSE:: This study aimed to evaluate Descemet membrane reflectivity using anterior segment optical coherence tomography (AS-OCT) in eyes with Fuchs endothelial corneal dystrophy (FECD). METHODS:: We retrospectively assessed 144 eyes of 88 consecutive participants (41 FECD, 15 pseudophakic bullous keratopathies [BKs], and 32 healthy controls, 63.5 ± 16.5 years). FECD was graded 0 to 3 based on the guttae areas using specular microscopy. The sum of AS-OCT reflectivity of the 3-dimensional volume from 10 μm thickness from the endothelial surface of the cornea and residual stromal area was calculated as Dsum(endo) and Dsum(stroma) in the central area of 3- and 6-mm diameters, respectively. The DES ratio was defined as the ratio of Dsum(endo) to Dsum(stroma). The percentage of the guttae area in the specular images was calculated using MATLAB. Dsum(endo) and DES ratio were compared among FECD, BK, and healthy controls. RESULTS:: Dsum(endo) in FECD grade 3 was significantly higher than that in healthy control eyes, FECD patients with mild and moderate guttae, and BK (all P ≤ 0.040). The DES ratio in FECD patients with mild to severe guttae (grade 1–3) was significantly higher than that in healthy control eyes and BK (all P ≤ 0.035). The percentage of the guttae area was significantly correlated with Dsum(endo) (R = 0.488, P < 0.001 for 3 mm, R = 0.512, P < 0.001 for 6 mm) and DES ratio (R = 0.450, P < 0.001 for 3 mm, R = 0.588, P < 0.001 for 6 mm). CONCLUSIONS:: Descemet membrane reflectivity in AS-OCT can be objective biomarkers for assessing guttae and FECD severity from early to end-stage FECD.