BACKGROUND: Patients with advanced gastric cancer (AGC) are often treated with irinotecan monotherapy as salvage-line therapy. However, the survival benefit of this therapy remains to be elucidated. METHODS: Medical records of AGC patients who were treated with irinotecan monotherapy as salvage-line treatment in six institutions from 2007 to 2014 were reviewed. RESULTS: A total of 146 patients had prior fluoropyrimidine and taxane therapies, and 75.3% had prior platinum therapy. The median age was 66 (range 27-81) years, and 102 males (69.9%) were included. Performance status (PS) was 0/1/2/3 in 53/70/19/4 patients. Eighty-nine patients (61.0%) had two or more metastatic sites. Irinotecan monotherapy as 3rd-/4th-line therapy was performed in 135/11 (92.5%/7.5%). The median number of administrations was 4 (range 1-62). Forty-six patients (31.5%) required initial dose reduction at the physician's discretion. The overall response rate was 6.8%, and the disease control rate was 43.1%. The median PFS was 3.19 months [95% confidence interval (CI) 2.30-4.08 months], and the median OS was 6.61 months (95% CI 5.94-7.28 months). Grade 3/4 adverse events were hematological toxicity (46 patients, 31.5%) and non-hematological toxicity (50 patients, 34.2%). Hospitalization due to adverse events was required in 31 patients (21.2%). Patients with relative dose intensity (RDI) less than 80% showed similar survival to those with RDI 80% or higher. CONCLUSIONS: Irinotecan monotherapy was relatively safely performed as salvage-line treatment for AGC in Japanese clinical practice. Careful patient selection and intensive modification of the dose of irinotecan might possibly be associated with favorable survival.