The present invention relates to synthetic saccharides of general formula (I) that are related to Streptococcus pneumoniae serotype 4 capsular polysaccharide and conjugates thereof. Said conjugate and a pharmaceutical composition containing said conjugate are useful for prevention and/or treatment of diseases associated with Streptococcus pneumoniae, and more specifically of diseases associated with Streptococcus pneumoniae serotype 4. Furthermore, the synthetic saccharides of general formula (I) are useful as marker in immunological assays for detection of antibodies against Streptococcus pneumoniae bacteria.