Advanced cancer patients with good performance status (PS) sometimes show poor prognosis despite receiving some chemotherapies. We evaluated prognosis of chemo-naïve advanced biliary tract cancer (ABTC) patients with good PS by Glasgow Prognostic Score (GPS). Sixty-two patients with Eastern Cooperative Oncology Group PS 0 or 1 were retrospectively analyzed, using multivariate Cox regression. GPS was defined with serum levels of two parameters, albumin >3.5 g/dl and C-reactive protein <1.0 mg/dl (both as 0, either as 1, and neither as 2). PS 0 (n = 32) and 1 (n = 30) patients had similar survival (P = 0.98). The median overall survival (OS) was 17.0 months for GPS 0 (n = 19), 14.2 months for GPS 1 (n = 17), and 6.4 months for GPS 2 (n = 26). GPS 2 had significantly shorter OS than GPS 0 (P = 0.002) or 1 (P = 0.033). Multivariate analysis identified two independent prognostic factors: GPS (hazard ratio 0.60, 95 % confidence interval 0.40-0.90, P = 0.012) and liver metastasis (hazard ratio 0.43, 95 % CI 0.20-0.90, P = 0.026). GPS was useful for chemo-naïve ABTC patients with good PS.