The present invention relates to novel crystalline forms of ceftaroline fosamil and to methods for their preparation. Furthermore the present invention relates to the use of the novel forms of ceftaroline fosamil for the preparation of an antibiotic medicament. In addition the present invention relates to pharmaceutical compositions comprising an effective amount of the novel forms of ceftaroline fosamil and to methods of preparing the same. Finally the present invention relates to pharmaceutical combinations comprising an effective amount of the novel forms of ceftaroline fosamil and β-lactamase inhibitors.