Background: Diagnostic imaging plays an important role in the evaluation of abdominal masses. Many imaging modalities are available ranging from conventional modalities to the cross-sectional modalities like USG, CT and MRI. The main principles of imaging are to determine the origin of mass, its measurement, extent, characterisation and assessment of its effect on contiguous organs. In the past, the mainstay was conventional imaging modalities like plain radiograph, Gastrointestinal contrast studies and I.V.U. Modern imaging modalities allow an early and accurate pre-operative diagnosis resulting in a higher rate of surgical resection and improvement of survival. Methods: A Cross-sectional observational study was done in 30 patients. Patients of either sex of any age group who had presented with involvement of retroperitoneal organs detected by routine ultrasound and postoperative patients with recurrence were included in our study. Results: Ultrasound is the initial imaging modality of choice since it is inexpensive, easy to perform and no radiation exposure. On USG, the retroperitoneal masses are classified as solid or cystic or mixed. Since most of the retroperitoneal masses have hetroechoic/mixed pattern, they cannot be characterized by ultrasound alone and hence need further evaluation. Conclusions: Multidetector computed tomography is the imaging modality of choice for further evaluation and characterization. CT protocol for evaluation of the retroperitoneum consisted of both non-enhanced and contrastenhanced scans for localisation and characterisation of the masses. Multiplanar reconstructions allowed the images to be viewed in any plane chosen including a curved plane thus helping in defining the exact location and extent of the lesion. With MIP and volume rendered images, the relationship of the vessels with the mass lesions was clearly visualized.