Syphilis is a chronic systemic infectious disease caused by the bacterium Treponema pallidum. Gastric involvement and nephrotic syndrome are uncommon but well documented complications of syphilis, but the co-occurrence of these two complications in the same patient is extremely rare. Thus, because of their nonspecific presentation, suspicion of gastric syphilis (GS) and nephrotic syndrome is essential for diagnosis. Patients should be investigated thoroughly and a diagnosis made based on clinical, endoscopic, and histological findings, in order to initiate appropriate therapy. We report of a 34-year-old male patient with a history of epigastric pain and a diagnosis of GS and syphilis-associated membranous glomerulonephritis confirmed by gastroscopy and kidney biopsy, who was treated successfully with penicillin G benzathine. This case report provides information on the typical features of GS that should help raise awareness of this rare disease entity among clinicians, resulting in earlier diagnosis and administration of appropriate therapy.