Objective: The objective was to study the incidence and risk factors for an early rise in intraocular pressure (IOP) following pars plana vitrectomy (PPV) for proliferative diabetic retinopathy (PDR) and to correlate its impact on visual outcome. Materials and Methods: This was a longitudinal prospective study. IOP and best corrected visual acuity (BCVA) for 73 cases of PDR (52 males and 21 females) who underwent PPV were recorded at day 1, week 1, and months 1, 3, and 6. Risk factors for the early IOP rise, defined as IOP ≥ 30 mmHg at day 1, were evaluated using cross-tabulation and the t-test. Results: Mean IOP at day 1 was 21.8 ± 9.8 mmHg with 15 cases (20.5%) having an early rise in IOP. Risk factors for the early IOP rise included intraoperative fibrovascular frond removal (P = 0.003), lens removal (P = 0.043), and intraoperative vitreous bleed (P = 0.008). The early rise in IOP was also associated with consistently raised IOP (P = 0.02), defined as IOP > 21 mmHg during first three consecutive follow-up visits. Further, difference in BCVA at 6 months among the two groups, i.e., with and without an early IOP rise was statistically significant (3.11 ± 1.52 logMAR vs. 2.11 ± 1.49 logMAR; P = 0.025). Conclusion: An early rise in IOP is a significant risk factor which compromises the visual outcome of patients undergoing diabetic vitrectomy.