Abstract Lessons Learned Irinotecan could not be proven noninferior to paclitaxel as a second-line treatment for patients with metastatic or recurrent gastric cancer. The failure to demonstrate noninferiority may have been a result of insufficient patient enrollment. Both agents were tolerable but showed different toxicity profiles. Background This phase III study compared the efficacy and safety of paclitaxel versus irinotecan in patients with metastatic or recurrent gastric cancer (MRGC) who had experienced disease progression following first-line chemotherapy. Methods Patients were randomized to receive either paclitaxel (70 mg/m2; days 1, 8, 15, every 4 weeks) or irinotecan (150 mg/m2 every other week). The primary endpoint was progression-free survival (PFS). Results This study was stopped early due to low accrual rate. A total of 112 patients were enrolled; 54 were allocated to paclitaxel and 58 to irinotecan. Median PFS for the paclitaxel and irinotecan groups was 3.5 and 2.1 months, respectively (hazard ratio [HR], 1.27; 95% confidence interval [CI], 0.86–1.88; p = .234). Noninferiority of irinotecan to paclitaxel was not proved because the upper boundary of the 95% CI (1.88) exceeded the predefined upper margin of noninferiority (1.32). Median overall survival (OS) was 8.6 months in the paclitaxel group and 7.0 months in the irinotecan group (HR, 1.39; 95% CI, 0.91–2.11; p = .126). Among toxicities greater than or equal to grade 3, neutropenia (11.5%) was the most common, followed by peripheral neuropathy (7.7%) in the paclitaxel group, and neutropenia (34.5%) followed by nausea, vomiting, and anemia (8.6%, respectively) in the irinotecan group. Conclusion Although paclitaxel showed numerically longer PFS and OS compared with irinotecan, this was statistically insignificant. Both irinotecan and paclitaxel are valid second-line treatment options in MRGC.