Background: To evaluate the impact of timing and extent of cytoreduction on the survival of patients with EOC before (2002-2008) and after (2009-2018) the introduction of aggressive debulking. Methods: A retrospective review of 195 patients with Stages IIIC and IV EOC who underwent debulking between 2002-2018 (Group#1: G1:(2002-2008), and Group#2: G2:(2009-2018). Medical and surgical variables related to PFS and OS were analyzed. Results: Compared to patients in G1, more patients in G2 had neoadjuvant chemotherapy (NACT) and interval debulking surgery (IDS) [56%(39/70 Vs. 76%(95/125) Vs), p = 0.003], had complete debulking (CD) [44%(31/71) Vs. 79%(103/131), P-value < 0.001]including [diaphragmatic resection [6%(4/72) Vs. 48%(63/131) p < 0.001], bowel ressection [15%(11/72) Vs. 37%(48/131), p = 0.001], peritnoectomy [11%(8/72) Vs. 62%(81/131) p < 0.001], and lymph node dissection [8%(6/72) Vs. 26%(34/131) p = 0.003] .More patients in G2 received Bevacizumab than in G1 [59%(38/65) Vs. 14%(4/29), p < 0.001]. More patients who had ACT and IDS had CD than optimal debulking (OD) than patients who had (PDS) (adjusted odds ratio (aOR) = 1.89, 95% CI: 0.98,3.6). After 2008, there was an increase in the number of patients with high tumor load and lower performance status who were referred for NACT and IDS. In patients with stage IIIC and IV, median PFS was longer in patients who had CD Vs. OD [in stage IIIC: 24 months, 95% CI: 21,27 Vs. 19 months, 95% CI: 17, 21, HR = 0.4, p = 0.006 respectively] [in stage IV: 18 months, 95% CI: 16,20 Vs. 14 months, 95% CI: 9,18, HR = 0.4, p = 0.1 respectively].Patients with stage IIIC who had PDS Vs. NACT and IDS had a non-statistically significant longer PFS [24 months, 95% CI; 20,27 Vs. 19 months, 95% CI: 17,21, HR = 0.8, p = 0.3]. Moreover, in stage IV, there was no difference in PFS in NACT and IDS Vs. PDS [16 months, 95% CI: 12,20 Vs. 17 months, 95% CI: 15,19 HR = 0.8, p = 0.7 respectively]. However, the timing and extent of the cytoreductive surgery did not significantly affect OS in both stages IIIC and IV. Conclusions: In Stage IIIC EOC, the extent but not timing of debulking surgery has the greatest impact on PFS. Longer follow-up is needed to assess the impact on OS.