OBJECTIVES: Several studies have considered the change in the price of medicines once a medicines patent expires and exclusivity in the market place is lost. Some HTA bodies consider the implications of patent expiry (e.g. PHARMAC) however the potential impact is not considered in the NICE reference case. The aim of this study was to consider how including the costs of medicines after patent expiry could impact cost-effectiveness results.  METHODS: A targeted review was conducted to identify any studies which had considered the impact of patent expiry. The approaches were compared and contrasted. A review of recent treatments that have received negative reimbursement decisions from HTA bodies were considered to determine if generic pricing could have influenced the decision making process.  RESULTS: Patent expiry has potential to impact results, however only in a handful of selected disease areas. The assumptions required to implement generic pricing after patent expiry can be associated with considerable uncertainty, particularly around the generic price of medicine. Further to this, the impact that generic pricing has is dependent on both duration of treatment and life expectancy of modelled populations. CONCLUSIONS: Patent expiry offers manufactures a chance to reduce the cost associated with treatment without altering health outcomes. However this is likely to offer a comparable discount to a majority of comparators available in the market, therefore it is likely this will offer the biggest benefit to the manufactures that implement it first.