Background: Acquired von Willebrand disease (AvWD) is a rare and often underdiagnosed disease that typically is associated with lymphoproliferative, cardiovascular disease, and myeloproliferative disease. It is challenging to diagnose as it requires a hemostatic challenge to present itself. Case Presentation: This is a 46-year-old male with a history of multiple sclerosis complicated by neurogenic bladder who presented with intermittent gross painless hematuria. He underwent a gross hematuria workup. Cystoscopy demonstrated active bleeding from the right ureteral orifice. CT Urogram showed a filling defect in the right renal pelvis and endophytic 3 cm solid, enhancing left kidney mass. The patient underwent diagnostic cystourethroscopy, bilateral retrograde pyelogram demonstrating no filling defects bilaterally. Right ureteropyeloscopy demonstrated diffuse patchy erythema of the infrarenal collecting system with biopsies obtained. His postoperative course was complicated by gross hematuria requiring cystoscopy which demonstrated no upper tract bleeding and small pulsatile bleeding vessel in the bladder requiring cauterization. Hematology was consulted to rule out bleeding diathesis with workup demonstrating a von Willebrand deficiency (vWD). He had no family history of vWD and an AvWD was suspected. Hematologic workup was consistent with AvWD, type 2B vWD also known as a platelet-type von Willebrand disease. Renal pelvis biopsies were negative for pathology. Further investigation of the left renal mass confirmed a biopsy-proven clear cell renal cell carcinoma (ccRCC). He underwent a laparoscopic left radical nephrectomy with final pathology demonstrating pT1 ccRCC with negative margins. Postoperatively his repeat laboratories demonstrated normal factor VIII activity, ristocetin cofactor, and vWF antigen with normalized activated partial thromboplastin time. Follow-up imaging demonstrated no further evidence of disease supporting the hypothesis of a paraneoplastic syndrome from his ccRCC that caused an AvWD. Conclusion: This is the first case report to our knowledge of a paraneoplastic AvWD secondary to ccRCC. This should be on your differential when there is abnormal bleeding in the setting of renal masses.