To compare the surgical and clinical outcomes of 27-gauge vitrectomy and 23-gauge vitrectomy. We conducted a single-center, prospective, randomized study. Fifty-three patients affected by vitreoretinal interface disorders (epiretinal membranes and macular holes) were randomly scheduled to undergo 27-gauge (28 patients) or 23-gauge (25 patients) pars plana vitrectomy. The presence of any potential factor of increased baseline inflammation or eye anatomy influencing the surgery was criteria for exclusion. The time of surgery, postoperative intraocular pressure (IOP), state of sclerotomy wounds, rate of complications, postoperative pain, and indicators of inflammation were studied. We also introduced a new parameter to compare intraocular inflammation after surgery, given by the change in the number of intraretinal hyperreflective foci (HRF). The 27-gauge vitrectomy was 1.28 min longer than 23-gauge vitrectomy (P < 0.05). The day after surgery, the mean IOP value was significantly higher in the 27-gauge group (16.12 mmHg versus 13.04 mmHg in the 23-gauge group,P < 0.05), but this difference disappeared in successive follow-ups and the sclerotomy wounds closed after 2 weeks in the both groups. The rate of postoperative hypotony did not significantly differ in the two groups (10.71% in the 27-gauge group and 8% in the 23-gauge group the day after the surgery,P = 0.94). Less postoperative eye redness was seen in 27-gauge eyes (value 1 on the scale) compared to 23-gauge (value 2 on the scale) (P < 0.05), but there was no significant difference in intraocular inflammation (cells, Tyndall, and number of HRF,P > 0.05 for all). The 27-gauge vitrectomy may have better outcomes in terms of IOP maintenance and cause less redness after the surgery but with a slightly prolonged surgery time and no other differences under other parameters (inflammation, rate of complications, postoperative pain, visual gain, and closure of the sclerotomy wounds).