Introduction: C3 glomerulopathy (C3G) is a rare complement-mediated renal disorder with incidence estimated to be around 1-3 cases per million people. C3G results from dysregulation of the alternative complement pathway driven by acquired factors namely autoantibodies that target C3 or C5 convertases. It is characterized by predominant C3 deposition in the glomeruli and commonly presents with features overlapping post-infectious glomerulonephritis, making diagnosis challenging in pediatric practice. Case presentation: A 15-year-old female presented with edema for 15 months, cola-colored urine, and persistent proteinuria. She was also noted to have hypertension at presentation. Laboratory investigations revealed persistent hypocomplementemia with low serum C3 and normal C4 levels. Urinalysis confirmed significant proteinuria with microscopic hematuria.Renal biopsy was performed due to prolonged symptoms and persistent complement abnormalities. Microscopy showed segemental sclerosis with podocyte hypertrophy suggestive of membranoproliferative glomerulonephritis. Immunofluorescence demonstrated dominant C3 deposition with minimal immunoglobulin staining, consistent with C3 glomerulopathy . Histopathological findings supported the diagnosis. She was initiated on antihypertensive therapy , renin–angiotensin system blockade(enalapril), and immunomodulatory treatment (steroid, mycophenolate mofetil), with close monitoring of renal function and proteinuria. Discussion: C3Glomerulopathy(C3G )should be suspected in adolescents presenting with prolonged hematuria, proteinuria, hypertension, and persistent low C3 levels. Differentiating it from post-infectious glomerulonephritis is crucial, as C3G carries a higher risk of progression to chronic kidney disease. Conclusion: This case emphasises the importance of early recognition and timely renal biopsy in children with persistent symptoms of hematuria, proteinuria ,urinary abnormalities and hypocomplementemia to prevent long-term renal complications.