AIM: To investigate the relationship between the size of macular holes and the possible benefit of internal limiting membrane (ILM) peeling. METHODS: 84 consecutive cases of idiopathic macular hole followed up for at least 3 months were included in this retrospective study. Surgery comprised pars plana vitrectomy, peeling of any epiretinal membrane, 17% C2F6 (hexafluoroethane) gas filling and 10 days of positioning. 36 eyes had ILM peeling. The main outcome measure was the macular hole closure rate checked by optical coherence tomography. RESULTS: The overall postoperative closure rate was 90.5%. For macular holes > or =400 microm in diameter, the rate was 100% with ILM peeling versus 73.3% without (p = 0.015). For smaller macular holes, the rates were 100% in both groups. Postoperative gain in visual acuity was not significantly different in eyes with ILM peeling and those without. CONCLUSIONS: ILM peeling does not seem to be useful for macular hole <400 mum in diameter. Its likely benefit has to be investigated for larger macular hole sizes, for which the failure rate is higher.