The objective of this study was to evaluate retrospectively correlations between catheter placement methods and treatment outcomes of patients treated with hepatic arterial infusion chemotherapy for unresectable liver metastases from colorectal cancer. This study involved 135 patients with liver metastases from colorectal cancer who underwent intrahepatic chemotherapy using catheter-port systems. Complications, treatment discontinuation, hepatic progression, and survival of patients treated with each method were evaluated retrospectively using the Kaplan-Meier method. Conventional 5-French end-hole catheter placement (n = 10) was compared with three side-hole catheter placement methods: 5-French side-hole catheter placement with a fixed catheter tip (original fixed catheter tip method, n = 77); long tapered side-hole catheter placement using a fixed catheter tip method (modified fixed catheter tip method, n = 24); and long tapered side-hole catheter inserted distally in the hepatic artery (long tapered catheter placement method, n = 24). The following treatment outcomes were significantly better for patients treated using the original or modified fixed catheter tip or long tapered catheter placement method than for those treated using the conventional method, respectively: hepatic arterial patency (1 year: 76.3%, 95.0%, and 94.4% vs 38.9%; p = 0.0014, 0.0007, and 0.0006), catheter stability (1 year: 96.7%, 95.5%, and 95.2% vs 42.9%; p < 0.0001, p = 0.0003, and p = 0.0009), time to treatment discontinuation (medians: 11.7, 14.4, and 12.4 vs 3.2 months; p < 0.0001, 0.0002, and 0.0019), time to hepatic progression (medians: 14.7, 15.7, and 15.8 vs 5.5 months; p = 0.0049, 0.0141, and 0.0004), and overall survival (medians: 21.1, 22.5, and 23.1 vs 13.1 months; p = 0.0146, 0.0036, and 0.0017). Compared with the conventional method, side-hole catheter placement methods allowed long-term intrahepatic chemotherapy and resulted in improved survival.