This article presents the results of a study on doctor–patient interaction in dyadic and triadic exchanges. The analysis is based on transcripts of recordings done at healthcare centres in northern Madrid, Spain, and Minneapolis, USA. The methodological approach is that of institutional discourse analysis as developed by Drew and Heritage (Drew & Heritage 1992; Heritage 1995, 1997; Drew & Sorjonen 1997). Three different types of doctor–patient interaction are examined: (1) doctor/foreign-language patient; (2) doctor/ foreign-language patient/ad hoc interpreter; (3) doctor/ foreign-language patient/trained interpreter. Topics such as the assignment of participant roles, changes in the general structure, turn-taking, and asymmetrical relationships will be explored. The study is mainly descriptive and qualitative, but also includes some comparative quantitative analyses.