Much has been written about the significance of patients’ literacy and language skills in the healthcare process, but there has been little critical analysis of the theories of language that underpin research and policy in this field. Discussions of the research methods and approaches that inform studies on patients’ reading and writing in healthcare settings are scarce. This paper presents a framework for studying the role of written language provided by healthcare institutions. It suggests an alternative to the narrow notions of health literacy that currently dominate the field. In order to illustrate this framework, the paper offers a detailed analysis of one particular case – the role of a patient information leaflet in the diagnostic process. The approach that is suggested draws on a combination of critical discourse analysis with ethnography.