OBJECTIVES: For orphan drugs an additional benefit is granted by market authorization of the EMA. In case orphan drugs exceed an annually turnover of 1m Euro (based on ex. pharmacy prices) in the outpatient sector recently authorized orphan drugs have to undergo an assessment of the additional benefit extent by the Federal Joint Committee. Based on the results pharmaceutical manufacturer and the head association of the statutory health insurance negotiate rebates. The objective of this analysis is to assess whether the additional benefit extent of orphan drugs does impact the rebate size of the price negotiations. METHODS: In a first step orphan drugs affected by an assessment of additional benefit extent were analyzed within the German market. The dependency between additional benefit extent and rebate size of negotiations is assessed by correlation analysis. This analysis is based on relevant public available data of the Federal Joint Committee as well as price related rebate information related to the AMNOG process for orphan drugs. RESULTS: By May 2015, 10 of currently 77 in Germany registered orphan drugs passed the AMNOG legislation comprising the assessment of additional benefit extent as well as associated price negotiations. Thereby rebates sizes ranging from 9% up to almost 44%. The analysis of the additional benefit extent and the rebate size showed no correlation between the two parameters. CONCLUSIONS: The hypothesis of an inversely proportional dependence between additional benefit extent and rebate size was refuted by this analysis. Following this a larger benefit extent tends not to impact price negotiations in terms of a rebate reduction.  However, the small sample size tends to limit power of the analysis.