Background Renal leiomyomas are exceptionally rare, benign, mesenchymal tumours originating from smooth muscle in the kidney. Historically, because of their small size, most renal leiomyoma cases were discovered incidentally based on autopsy findings. However, since the advent and improved access to imaging modalities such as ultrasound and computed tomography (CT), renal leiomyomas are being discovered more frequently. Although usually incidental discoveries, clinical presenting signs and symptoms comprise abdominal or flank pain, a palpable flank mass, and haematuria in 20% of those with symptoms. Case presentation We study the case of an incidentally found, asymptomatic, left kidney mass that presented in a 60-year-old female. Initial suspicions on CT imaging of either renal cell carcinoma or oncocytoma resulted in a radical nephrectomy of the left kidney. Postoperative pathological examination of the mass revealed a renal leiomyoma; a rare, benign tumour that is mostly indistinguishable from malignant tumours on imaging. Conclusions With the current availability of ultrasonography and CT, they are often discovered incidentally, and the radiological differential diagnoses are often inadequate or challenging in such cases. The gold standard management of these suspicious cancer cases is still a radical nephrectomy with postoperative pathological and immunohistochemical analysis. Due to its benign nature, patients enjoy excellent prognoses without recurrence. We discuss and briefly review the relevant literature of the clinical, imaging and pathological features of renal leiomyomas and those of the differential diagnoses.