A potential challenge of using radiotracer 68-Ga-PSMA for detection and staging of prostate cancer in PET/MR is a frequently observed halo-artifact around the urinary bladder caused by improper scatter correction (SC). Tumor manifestations in these regions might be non-detectable or show distorted SUVs. To evaluate the impact of SC on 68-Ga-PSMA PET/MR imaging, PET data sets of 100 patients were reconstructed twice using standard and improved SC. The improved SC significantly reduces the halo-artifact around the bladder. Measured SUVs in the halo margin on average increased by 325 %, and therefore, considerably affect quantitative assessment of prostate cancer in PET/MR.