This paper reviews how the interpreter's role is described in empirically based, qualitative cross-cultural interview studies and how trustworthiness is determined. Increased immigration during the past decades has created a multiethnic society in many countries. This development poses a challenge to healthcare staff, in that they need to understand how people from different cultures experience health and illness. One way to assess immigrants' experiences is through cross-cultural interview studies, involving an interpreter. Thorough knowledge of the interpreter's role is needed in order to increase the trustworthiness of this kind of nursing research. Literature searches were conducted from October to November 2004 using PubMed, CINAHL, Psycinfo, Sociological abstract, Your Journals@ovid, and Eric databases. Qualitative interview studies written in English and performed with an interpreter were included. The Matrix Method was used to review the literature. In almost all of the 13 relevant papers found, the role of the interpreter(s) in the research process was only sparsely described. In addition, all studies except one employed different techniques to established trustworthiness. The most common techniques were prolonged engagement, member check or triangulation, the latter performed either on the data, investigators or methods. Methodological issues with respect to interpreters have received only limited attention in cross-cultural interview studies. Researchers in the field of nursing need to consider (1) the interpreter's role/involvement in the research process; (2) the interpreter's competence and the style of interpreting; (3) the interpreter's impact on the findings. This information is a prerequisite when trying to determine the trustworthiness of a cross-cultural study.