Paraneoplastic syndromes (PNSs) describe a constellation of complex signs and symptoms, distinct from those caused by the direct impact of the tumor itself, resulting from the elaboration of various tumor-associated proteins. These syndromes can cause substantial distress and impact quality of life and outcomes for patients. In this chapter, paraneoplastic syndromes commonly observed with genitourinary malignancies including cancers of the kidney, prostate, bladder, testicle, adrenal, and penis are reviewed, with attention to their prevalence, presentation, etiology, mechanisms, as well as optimal management strategies.