OBJECTIVES: This study aimed to estimate the cost per treatment failure avoided of topical preservative-free moxifloxacin (MOXI) as compared with ofloxacin (OFLOX), marketed as preserved Trafloxal and preservative free Trafloxal E.D.O.in the treatment of acute infectious conjunctivitis in The Netherlands (NL). METHODS: A survey amongst GPs and Ophthalmologists (OPH) collected health care resources(HCU) used to manage acute bacterial conjunctivitis.  Cost  of health care resourses were obtained from National databases; treatment failure rates were estimated from a meta-analysis of  randomized controlled trials(RCT) investigating MOXI.  A decision tree model in Treeage  was populated to define the cost per treatment failure avoided using MOXI instead of OFLOX. OFLOX treatment failure rate was obtained from a trial directly comparing OFLOX with MOXI. Probabilistic sensitivity analysis was performed investigating the range of HCU used in clinical practice by different OPH and investigating the uncertainty around treatment failures reduction. RESULTS: The average estimated incremental cost per treatment failure avoided  by a GP was €53.47 and €215€ by an OPH (range €169.55€ to €279.42).  The treatment failure rate for MOXI was 2.9% [with 95% CI 1.4%,4.3%] versus 7.6% for  OFLOX. The price for MOXI taken in the model was €14.04,  the maximum reimbursement of current preservative free antibiotic treatments in NL.  A weighted current average price of Trafloxal (110,943 units) and  Trafloxal E.D.O.(15,554 units) was €3.74.  With a failure rate less than half that for OFLOX, and assuming a willingness to pay (WTP) of 100€ per treatment failure avoided (based on the WTP for avoiding allergic reactions), in 90% of the simulations MOXI is cost-effective.  CONCLUSIONS: Use of topical moxifloxacin instead of ofloxacin avoids treatment failures. Moxifloxacin, with a price of 14,04€ is  a cost-effective alternative to ofloxacin given a willingness to pay of €100 per treatment failure avoided.