Elevated body mass index (BMI) is associated with an increased risk of biochemical failure (BCF); however, BMI may not best capture underlying health. We examined a different metric, liver fat, which may better approximate the body's metabolic state, to see its association with time to biochemical failure (TTBCF) in patients treated definitively for prostate cancer. Of 210 patients who received a PSMA PET/CT at our institution, we identified 60 men treated with either prostatectomy or definitive radiation without androgen deprivation therapy who developed BCF. BCF was defined as PSA ≥ 0.2 ng/mL if treated with prostatectomy or PSA nadir + 2 ng/mL for those treated with definitive radiation. All prostatectomy patients had a post-op PSA < 0.1. Liver fat was evaluated via the non-contrast portion of respective PSMA PET/CT scans. Average Hounsfield Units (HU) of the liver were used to split individuals into high (≤ 56.1) and low (> 56.1) liver fat. A threshold of 56.1 HU was chosen as it corresponds to 5.56% liver fat, or the 95th percentile of non-obese, non-diabetic controls. Liver fat was quantified by converting HU to proton density fat fraction (PDFF) using the formula: PDFF = -0.582*HU + 38.214. Median TTBCF was estimated using Kaplan Meier methods, and Cox Proportional Hazards Regression was used for covariate adjustment. Forty-four patients were classified as having high liver fat (HLF) and 16 as having low liver fat (LLF). Patients with HLF were more likely to have a higher BMI, have high risk disease, undergo surgery, and have shorter TTBCF (Table). When adjusted for NCCN risk category and treatment type, HLF was associated with twice the risk of BCF per unit time (aHR = 2.02, 95% CI [1.09 - 3.73], p = 0.03). With additional adjustment for BMI (continuous), HLF was no longer an independent predictor of TTBCF (aHR = 1.75, 95% CI [0.94 - 3.25], p = 0.08). In this small study of patients who had biochemical failure after completing definitive treatment to the prostate, those with liver fat ≥ 5.56% were more likely to fail sooner, adjusting for risk category and treatment type. This project suggests that a man with elevated liver fat, on average, experiences a shorter interval free from prostate cancer.