OBJECTIVES:  To assess if there is a difference on how payers value rarity in drug pricing between oncology and non-oncology orphan drugs in France, Germany, Italy, Norway, Spain, Sweden, UK. METHODS:  Approved orphan drugs with their respective disease prevalence were extracted from the European Medicines Agency website and were divided into oncology and non-oncology. The annual treatment costs for each drug were computed based on the summary of product characteristics (SmPC) using ex-factory prices from IHS POLI and country price databases. The relationship between the prevalence (rarity) and the annual treatment cost of (price) in each country was analysed using simple regression analysis. The correlation coefficient (r) for oncology and non-oncology drugs were averaged and compared in each country. RESULTS:  A total of 120 orphan drugs were analysed. For both oncology and non-oncology orphan drugs, results show an inverse correlation between annual treatment cost and disease prevalence in all countries, with the treatment being more expensive the rarer the disease. For non-oncology drugs, statistical significance was reached in all countries except Spain and Sweden (France: r=-0.41, p=0.01; Germany: r=-0.41, p=0.01; Italy: r=-0.38, p=0.01; Spain: r=-0.37, p=0.08; UK: r=-0.40, p=0.002; Sweden: r=-0.47, p=0.06; Norway: r=-0.41, p=0.01). Oncology drugs had a weaker correlation except Spain (France: r=-0.36, Germany: r=-0.18, Italy: r=-0.25, Spain: r=-0.49, UK: r=-0.23, Sweden: r=-0.47, Norway: r=-0.29; all p˃0.05 except Spain p=0.03). CONCLUSIONS: This study shows an inverse correlation between annual treatment cost and disease prevalence in orphan drugs. A weaker correlation in oncology supports the idea that in this disease area, payers value other drivers aside from rarity which may include severity, the availability of treatment options, the size of clinical benefit, and incremental cost-effectiveness ratio. Pricing is a complex process where different attributes are assessed, however rarity is valued by payers in pricing decisions in all the countries.