Objective: Immunophenotypic characterization of high grade (pleomorphic) sarcomas and determination of their frequency, mean/median age, sex preferences and common sites in Pakistani patients. Methods: This study included 134 consecutive cases of high grade (pleomorphic) sarcomas diagnosed in adults above the age of 15 years in the section of histopathology at the Aga Khan University Hospital, Karachi during a period of two years. These high grade (pleomorphic) sarcomas were immunophenotyped using a panel including antibodies against Vimentin, Desmin, Smooth muscle Actin, S 100, CD34, CD68 and Cytokeratin etc by indirect immunoperoxidase. Results: Of the 134 cases which were characterized, 38.1% were pleomorphic leiomyosarcoma, followed by pleomorphic rhabdomyosarcoma 14.9%, Malignant Peripheral Nerve Sheath Tumour 9%, pleomorphic liposarcoma 3.7% and pleomorphic storiform Malignant Fibrous Histiocytoma 0.7%. Thirty three percent of cases could not be characterized further. Mean/ median age for Leiomyosarcoma was 50/50, for Rhabdomyosarcomas 33/22, for MPNST 42/41, for Liposarcoma 52/50 and for Malignant Fibrous Histiocytoma 46/46 respectively. The commonest site for leiomyosarcoma was lower limb (43%), for rhabdomyosarcoma head and neck (42%), for MPNST thorax (36.4%) and for liposarcoma abdomen (50%). Conclusion: It was concluded that the most common pleomorphic sarcoma occurring in our adult population was Leiomyosarcoma, and that immunohistochemical stains are essential in most cases for further characterization of pleomorphic high grade sarcoma.