Osteopetrosis (OP) is rare metabolic bone disease characterized by impaired osteoclastic bone resorption. It is inherited by autosomal dominant or recessive mode, with variable penetrance, resulting in variable severity. It can present with cytopenia’s, extramedullary hematopoiesis and neurological features like nerve compression. Hematopoietic stem cell transplant (HSCT) is the curative treatment for severe cases (Malignant Infantile Osteopetrosis- MIOT variant) however literature to support the same is very sparse. We report 3 patients with OP, two of which were successfully treated with HSCT using TTF (Thiotepa Treosulfan Fludarabine) conditioning. HSCT is curative in these patients with better outcome when done early.