Renal vein thrombosis (RVT) in the post-partum period is rarely reported. It is majorly a complication of the hypercoagulability associated with both pregnancy and postpartum state. We report the case of a primiparous 19-year-old woman, who presented to the Emergency Department complaining of acute right flank pain. Doppler ultrasonography revealed thrombosis of the right renal vein with extension into the inferior vena cava (IVC). Contrast-enhanced abdominal computerized tomography (CT) confirmed the diagnosis. The outcome was favorable after anticoagulation therapy by Heparin was initiated. Practitioners need to be aware of the diagnosis of RVT. Imaging tests, especially contrast CT scans play a major role in the diagnosis and post-therapeutic assessment.