In this review, macrocycles are defined as organic molecules containing at least one non-bridged cycle of 12 or more covalently connected atoms. Common statistical aspects as well as structure activity relationships (SAR) of macrocycles based on chemoinformatics methods are discussed. Can macrocyclic structural features be linked to activities against cancer cells, viruses like HIV, or bacteria? General challenges and problems in using chemoinformatics for more detailed analyses of macrocycles based on large compound databases are outlined.