The malignant peripheral nerve sheath tumour is the malignant counterpart to benign soft tissue tumours such as neurofibromas and schwannomas. Malignant Triton Tumour is a histological variant of malignant peripheral nerve sheath tumours with rhabdomyosarcomatous differentiation. They are known to develop in cases of neurofibromatosis type 1 (von Recklinghausen’s disease). Malignant peripheral nerve sheath tumor is biologically an aggressive tumour for which the treatment of choice is surgery. Here we report a rare case of malignant peripheral nerve sheath tumour, not associated with neurofibromatosis type 1 and arising in the retroperitoneum.