Contact lenses with adherent Serratia marcescens and Pseudomonas aeruginosa could not be sterilised either with polyaminopropyl biguanide or with chlorhexidine (CHX) commercial solutions meant for contact lens disinfection, even after treatment lasting 12 h. Ethyl-6-O-decanoyl glucoside (EDG) with chlorhexidine enhanced the killing significantly. The same was also found to be the case for dispersed cells of P. aeruginosa on cellulose acetate filters. EDG enhances the bactericidal effect of 0.00025 CHX by a mechanism not solely due to detergent action and is a potential adjunct to CHX in clinical applications.