The present invention relates to a liquid pharmaceutical composition suitable for parenteral administration comprising: a) pemetrexed diacid； b) at least one organic amine； c) at least one antioxidant； d) 10-200 mg/ml of propylene glycol； and e) one or more parenteral solvents, wherein the preparation thereof is conducted in an atmosphere of inert gas and wherein the organic amine(s) is present in an amount sufficient to reach a pH of the composition in the range from 8.3 to 9.1 The invention further relates to the use of said liquid pharmaceutical composition as medicament in the treatment of malignant pleural mesothelioma and non-small cell lung cancer.
