On 20 March 2012, the US Supreme Court handed down its much awaited patent-eligibility ruling in the dispute between Prometheus Laboratories Inc (‘Prometheus’), acting as plaintiffs, and Mayo Medical Laboratories (‘Mayo’), as alleged infringers of Prometheus' licensed patents. 1 The decision addresses primarily the US patent-eligibility of diagnostic methods and dosage regimes, but it could ultimately also affect the patent-eligibility of isolated or purified biological and chemical compounds. This case review will first briefly describe the background to the case and the patents at issue (section 1), the procedural history (section 2), and the judgment of the Supreme Court (section 3). This is followed by a brief discussion of the decision's actual and potential implications for the patentability of biomedical methods and products including some comparative European views (section 4). The paper concludes with general remarks (section 5).