Liposome-encapsulated vincristine is provided for treating a cancer such as a lymphoma, leukaemia or myeloma and especially non-Hodgkins Lymphoma or Acute Lymphocytic Leukaemia. The liposomes comprise sphingomyelin and cholesterol in a ratio between 75/25 (mol % sphingomyelin/mol % cholesterol) and 50/50 (mol % sphingomyelin/mol % cholesterol) and vincristine at a concentration of 0.1 to 0.5 mg/ml.