A series of highly preorganized, polyheterocyclic hosts for creatinine has been synthesized. Key receptors bearing intrinsic chromophores are ketones 4 and 9. H-1 NMR and UV-visible spectroscopy were used to detect extraction of creatinine hydrochloride by 4 into CDCl3 and 5% ethanol/chloroform, respectively. Receptor 9, which has an additional hydrogen-bond donor, binds creatinine in 70 % aq. methanol, as shown by changes in UV-visible absorptions at constant pH* (4.3). These hexagonal lattice receptors are the most effective complexing agents known to bind creatinine, which is a clinically important constituent of blood.