The subject matter of the invention is a method for preparing a vaccine composition comprising at least aluminium oxyhydroxide (AlOOH), and at least the hepatitis B surface antigen and the Haemophilus influenzae type b antigen. According to the invention, the hepatitis B surface antigen is kept adsorbed on the AlOOH, whereas the Hib antigen is kept nonadsorbed. To this end: the hepatitis B surface antigen is adsorbed onto AlOOH in order to obtain an AlOOH/HBsAg complex, then—said AlOOH/HBsAg complex is mixed with the Hib antigen in the presence of cationic amino acids at a concentration of at least 100 mg/l, and of phosphate ions at a concentration of 35 to 45 mMol/l.
