Renal stones are one of the most common diseases in the urology field that are easily diagnosed by one of the standard imaging techniques. Noncontrast spiral computerized tomography (CT) can detect up to 95% of the renal, ureteric and bladder stones, especially those with calcium composition, and considered nowadays one of the most accurate methods for detecting undetectable stones by other modalities. We report a case of a 60-year-old female who presented with colicky right flank pain due to large calcium oxalate renal stone that is undetected by standard imaging technique including spiral CT scan. Uretroscopy diagnosed and ultimately treat this patient problem.