Streptococcus pneumoniae (pneumococcus) is a major cause of morbidity and mortality especially in infants and elderly people. Pneumococcus capsular polysaccharide has been characterised and more than 90 different serotypes have been identified. Serotype-specific antibodies against the capsular polysaccharide are produced during infection.At present, many countries follow the WHO pneumococcal ELISA IgG measurement protocol, in which polysaccharides from ATCC are used as antigens. In recent years, serotype specific polysaccharides from different producers have been tested in pneumococcal antibody assay's. In this project, purified serotype specific pneumococcal antigens from SSI Diagnostica and from ATCC were compared. In general, the data showed that both types of polysaccharide could be used as antigens. Furthermore, the effect of adsorption using different combinations of adsorption procedures was tested, showing similar results using CWPSmulti or CWPS + 22F.