Lumichrome (Lc) is a photodegradation product of riboflavin. It is more photostable and a more efficient photogenerator of singlet oxygen than riboflavin. Lc absorbs mainly in the UVA range. Cyclodextrins (CDs) are reported to be very efficient solubility enhancers of Lc in aqueous solutions. A 1:1 inclusion complex has been predicted between Lc and α and βCDs (Terekhova, Kumeev et al. 2011). The aim of the present study was to evaluate the influence of CDs on solubility and on the bacterial phototoxicity of Lc in vitro.