To evaluate the safety and effectiveness of aflibercept in combination with fluorouracil, leucovorin, and irinotecan (FOLFIRI) in Korean patients with metastatic colorectal cancer (mCRC) who progressed with oxaliplatin-containing regimen.This was a prospective observational study conducted at 22 sites across Korea between February 2018 and September 2019. Patients aged > 19 years with a diagnosis of mCRC who were prescribed aflibercept plus FOLFIRI, after progression with an oxaliplatin-containing regimen were included. Disease assessment was performed every 6 weeks.A total of 185 patients were included (males, 58.9%; right-sided tumors, 23.8%; and ECOG performance factor ≥ 1, 68.6%). A total of 514 adverse events (AEs) occurred in 134 patients, of which 206 (49.2%; 95% CI 42.0%, 56.4%) events were considered as adverse drug reactions (ADRs), 172 unexpected AEs (49.7%; 95% CI 42.5%, 56.9%), and 53 serious AEs (22.2%; 95% CI16.2%, 28.2%). The most common serious ADR was pneumonia (n = 2, 1.6%). The most common all grade hematological AE and non-hematological AE were neutropenia (21.6%) and nausea (16.2%), respectively. Over a median follow-up of 5.6 months, a total of five grade 5 (1.0%) AEs were reported. Median OS was 9.4 months, and median progression-free survival (PFS) was 7.3 months. The overall response rate was 14.6%. Right-sided tumor location and prior bevacizumab treatment were independent factors of poor PFS in multivariate analysis.Aflibercept in combination with FOLFIRI was effective and showed an acceptable safety profile in Korean patients with mCRC in daily clinical practice.