Objective: The study proposed to assess the relation between the body mass index (BMI) and clinicopathological features of metastatic urinary bladder cancer (uBCa) and the influence on survival outcome. Method: A retrospective study included 201 metastatic uBCa patients. They classified into three groups according to BMI, group I; a BMI of 18.5 – 24.9 kg/m2, group II; a BMI of 25-29.9 kg/m2, and group III; BMI ≥ 30 kg/m2. The Kaplan – Meier curve used for survival analysis. Results: 69 patients (34.3%) belonged to group I, 75 patients (37.3%) belonged to group II, and 57 patients (28.4%) belonged to group III. Smoking history was detected in 44.8% of patients with Performance Status (PS) 0 in 55.2%, and PS 1 in 26.9%. Of note, 44.8% of patients responded to 1st chemotherapy and 50.7% The effect of body mass index on clinico-pathological features and survival outcome in metastatic bladder carcinoma Amrallah A. Mohammed 1, Ayman elshentenawy2, Fifi Mostafa Elsayed3 1 Medical Oncology Department, Faculty of Medicine, Zagazig University, Egypt. 1King Salman Armed Forces Hospital-Tabuk City, KSA. 2Kasr EL Einy center of clinical oncology and nuclear (NEMROCK), Cairo university, Egypt. 3Clinical Oncology & Nuclear medicine Department faculty of medicine Suez Canal University, Egypt. Corresponding Author: Dr; Amrallah A. Mohammed MBBCh, MSc, MD., Prof. of Medical Oncology, Faculty of medicine, Zagazig University, Egypt / Consultant of medical oncology in King Salman Armed Forces Hospital-Tabuk City, KSA., 29 Saad Zaghloul, Postal code, 44519, Egypt , E-mail: amrallaabdelmoneem@yahoo.com, T; 00201224141040 received more than 2 lines. Through the univariate analysis, poor prognostic outcome was associated with male (P= 0.01), smoking (P=0.002), BMI group II and group III (p=0.00), PS 2 compared with PS 0 (P<0.001), metastasis to liver, lung, and lymph node (P<0.001), and no response to first line chemotherapy (P<0.001). While no effect for age (P=0.1), bone metastasis (P=0.6), serum LDH (P=0.1), serum albumin (P=0.4), and ≥2 chemotherapy lines (P=0.5) on survival outcome. After the follows-up period, the OS was 12.7 months for all patients. Regarding the BMI groups, the median OS was 23.5 months, 12.9 months, and 10.2 months for group I, group II, and group III respectively (p=<0.001). Conclusion: High BMI associated with aggressive clinico-pathological features and poor survival outcome in metastatic uBCa.