AIMS: To evaluate the ocular axial length as a risk factor for development of central retinal vein occlusion (CRVO) and branch retinal vein occlusion (BRVO). METHODS: Ocular axial lengths were measured, by A-scan ultrasonography, in 17 patients with CRVO and 41 patients with BRVO and compared with those of contralateral unaffected eyes and 66 age matched controls. RESULTS: In 17 patients with CRVO the mean axial length of affected eyes was 22.25 (SD 0.19) mm and of unaffected eyes was 22.61 (0.13) mm. In 41 patients with BRVO the mean axial length of affected eyes was 22.89 (0.11) mm and of unaffected eyes was 22.99 (0.12) mm. CONCLUSION: These findings confirm that the axial lengths in CRVO and BRVO were significantly shorter than in the controls. This significant difference may be a risk factor in the development of CRVO and BRVO.