The present invention relates to well-defined synthetic saccharides of general formula (I) that are related to the repeating unit of Streptococcus pneumoniae serotype 5 capsular polysaccharide and conjugates thereof. The conjugates and pharmaceutical compositions containing said conjugates are useful for prevention and/or treatment of diseases associated with Streptococcus pneumoniae, and more specifically against diseases associated with Streptococcus pneumoniae serotype 5. Furthermore, the synthetic saccharides of general formula (I) are useful as marker in immunological assays for detection of antibodies against Streptococcus pneumoniae bacteria.