An adequate and timely diagnosis is crucial in the treatment of renal artery aneurysms during pregnancy since the risk of rupture and its catastrophic consequences are high. Clinical symptoms, laboratory results, and B-mode abdominal ultrasonography may mimic renal colic. In this report, a case of a pregnant 26-year-old woman with a large, symptomatic renal aneurysm is presented. The diagnostic pathway and the treatment are described. Potential pitfalls in the diagnosis are discussed.