This chapter explores the requirements engineering (RE) process and its application in blockchain for healthcare. Blockchain applications, such as Electronic Health Records (EHR) and clinical trial management systems, require structured RE methods to ensure privacy, security, and scalability. The chapter introduces the BC-SQUARE methodology, specifically tailored to blockchain, and explores its components such as non-functional requirements and block-point effort estimation. The chapter also highlights how BPMN modelling can simulate real-world scenarios, validate requirements, and optimize system performance.