The stable thrombin composition comprises purified thrombin, human albumin and a neutral salt, the resulting product being stable when stored as a lyophilisate or frozen and is adjusted to a nominal strength of 500 IU of thrombin or more per ml of solution, the human albumin being in a concentration of over 0.05% (w/v) and preferably between 0.1% (w/v) and 1% (w/v).