Clinco-morphological characteristics of malignant giant cell tumours of soft tissues in 31 patients are presented. Microscopically, the tumours consisted of histiocyte-like mononuclear cells possessing a phagocytic capacity, stretched out fibroblast-like cells forming collagen fibres, multinuclear giant cells of the type of osteoclasts. Three morphological variants were singled out: 1/ predominantly round-polygonal-cellular (histiocyte-like), 2/ predominantly spindle cell (fibroblast-like) and 3/ mixed. Clinically the tumours were divided into 2 groups: superficial (in 8 patients) and deep ones (in 23 patients) developed in skeletal musculature, deep fasciae and tendons, retroperitoneally, as well as in the mammary gland, mesentery of the small intestine, the stomach. The superficial tumours were characterized by relatively low malignancy. Prognosis in the majority of patients with deep tumours of soft tissues was unfavourable. The authors share the opinion of the investigators who consider these tumours to be a malignant variant of giant cell tumours of vagina tendinis and, bearing in mind the unestablished histogenesis of these tumours, think it expedient to retain the term "malignant giant cell tumours of soft tissues".