Diseases associated with persistent urachus are relatively rare. During the past 9-year period, there have been 14 patients with urachal disease consisting of 10 with urachal abscess and 4 with urachal cancer. The 10 patients with urachal abscess consisted of 7 males and 3 females aged 19-77 years (mean, 46 years). The 4 patients with urachal cancer consisted of 2 males and 2 females aged 48-81 years (mean, 57 years). As symptoms, lower abdominal pain was frequently observed in the patients with persistent urachus with abscess and gross hematuria in those with urachal cancer. Echo and magnetic resonance imaging (MRI) were useful for visualizing the lesion. Computed tomogtaphic (CT) scanning could not visualize the lesion in 2 patients. Nine patients underwent MRI, which visualized the lesion in all of them. As urachal abscess, an umbilical fistula was observed in 3 patients, urachal cyst in 4, and urachal diverticulum in 1. The preoperative diagnosis was urachal cancer in 6 patients, and pathological examination showed 4 patients with adenocarcinoma, 1 with inflammatory granuloma, and 1 with pseudosarcoma. Urachal abscess was treated by resection of the abscess in 6 patients, transurethral resection in 1, and resection of the umbilicus and urachus and total cystectomy in the other. Of the patients with urachal cancer, 1 underwent total cystectomy and the other 3 underwent total urachal resection and partial cystectomy. In 2 patients with persistent urachus with abscess, the differentiation between abscess and malignant tumor was difficult.