In Ireland, the National Centre for Pharmacoeconomics (NCPE) performs the pharmacoeconomic assessment of all new drugs seeking reimbursement by the Health Service Executive (HSE). The use of early phase clinical trial data in the pharmacoeconomic evaluations (for drugs for oncology and orphan diseases) has increased in recent years. The extent of this increase has not been investigated. There is an increased uncertainty when using early phase clinical trials to estimate clinical effectiveness. The internationally recognised pharmacoeconomic evaluation process does not currently capture all aspects of this uncertainty. There is an increased risk that the payer is paying a high price for a technology, which does not actually provide the promised health gain. Since drugs for use in oncology and orphan diseases are generally very costly, the associated opportunity costs are very high.