Background: Declines in nutrition status and changes in adverse body composition frequently occur in oncology patients including those with muscle invasive bladder cancer undergoing radical cystectomy (RC). Furthermore, RC frequently results in secondary surgical complications with as many as 60% of patients experiencing a complication within 90 days of surgery. Patient skeletal muscle and nutrition status assessed preoperatively may be predictors for adverse outcomes. The objective of this retrospective closed cohort study was to differentiate perioperative skeletal muscle area in patients with various nutrition statuses and describe hospital length of stay (LOS), readmission rates, and adverse surgical events after RC. Methods: Using diagnostic CT images, skeletal muscle index (SMI) at L3 was quantified and utilized as a marker for change in skeletal muscle and its association with mild to severe malnutrition in 43 patients with bladder cancer preoperatively. The Patient Generated Subjective Global Assessment (PG-SGA) was utilized to classify presence and severity of malnutrition. Patient adverse surgical events were classified using the Memorial Sloan-Kettering Secondary Surgical Events classification. Results: Half of all patients were at least 69 years old (48-87), majority were overweight (BMI >24.9), and 46% of patients were classified as moderately to severely malnourished. No significant trends were noted in SMI among mild or moderate-severe malnourished patients. Male SMI scores significantly decreased from baseline CT to recovery CT scan, while the same was not observed in female patients. No significant trends in rate of LOS, adverse surgical event grade, or readmissions among nutrition groups were observed. Conclusions: Loss of skeletal muscle mass and malnutrition is highly prevalent among patients with bladder cancer undergoing RC, however, further research is required to more adequately characterize multifactorial muscle loss during surgery treatment course and its association with standardized nutrition assessment tools.