We present a very rare case of laparoscopic colectomy for a patient with ascending colon cancer and an agenetic right kidney. A 57-year-old man visited our institute for further evaluation for a positive fecal occult blood test. Approximately, 20 years earlier, the right kidney of the patient was found to be congenitally absent. A physical examination indicated no anatomical anomalies in his genitourinary system, and the renal function was within the normal range. Total colonoscopy revealed a cancer of the ascending colon and laparoscopic colectomy was performed. The right colon was mobilized by lateral-to-medial extension of a retroperitoneal dissection between the fusion fascia and the anterior renal fascia. The right testicular vessels were preserved without injury to the anterior renal fascia; however, the right ureter could not be detected. The operation was performed safely. Thus, we believe that in patients with congenital unilateral renal agenesis, the anterior renal fascia is present, and laparoscopic ipsilateral colectomy can be safely performed in such patients.