·AIM: To compare choroidal thickness at the macula in eyes with unilateral idiopathic full - thickness macular holes (FTMH) with that of unaffected fellow eyes, and eyes of normal control patients. ·METHODS: Cross-sectional study. Thirty patients with unilateral idiopathic FTMH and thirty age, sex, and race-matched controls were recruited. Axial lengths were measured using laser interferometry. Enhanced depth imaging optical coherence tomography images were obtained using Heidelberg spectral - domain optical coherence tomography. Choroidal thickness was measured at the fovea, and at 1 mm and 2 mm nasally, temporally, superiorly and inferiorly from the center of the fovea. Statistical analysis was performed using independent and paired t-tests, chi-square tests, and Pearson correlation tests (P<0.05). ·RESULTS:The mean subfoveal choroidal thickness was 201.0±44.0 μ m in the FTMH group,225.3± 51.4 μ m in the fellow eye group and 262.3±70.3 μ m in the control group. The choroid was thinner in FTMH eyes at all locations when compared to control eyes(P<0.05). The fellow eye group also had thinner choroids than the control group at all locations except at 1 mm and 2 mm nasal to the fovea (P<0.05). Choroidal thickness in the FTMH group was lower than in the fellow eye group, but the differences were not statistically significant (P > 0.05). Choroidal thickness was generally highest subfoveally and lowest nasally. Subfoveal choroidal thickness was negatively correlated with age (r = -0.278, P = 0.032), and axial length (r=-0.328,P=0.011). ·CONCLUSION:Choroidal thickness is lower in both eyes of patients with unilateral FTMH compared to healthy control eyes.