There are widespread concerns about the increasing use of multiple medicines. The aims of this thesis were to identify older patients' and general practitioners' (GPs) attitudes to and experiences of multiple medicine use, as well as to describe patterns of multiple medicine use in different age groups in association with patient-related factors. An additional aim was to contribute to scientific methodological development by providing an empirical example of the application of the Lehoux, Poland, & Daudelin template for the analysis of interaction in focus groups. Data were collected via qualitative focus group discussions and from a cross-sectional community-based population survey conducted during 2001-2005. The patients revealed co-existing accounts of both immediate gratitude that medicines exist and problems with using multiple medicines such as worrying whether multiple medicine use is 'good' for the body. The patient-doctor relationship coloured their attitudes towards their treatment and care. The GPs at times felt insecure, though surrounded by treatment guidelines. Lack of communication with hospital specialists was perceived to reduce treatment quality, while influence of patient pressure was thought to contribute to the development of multiple medicine use. An interaction analysis helped in appreciating and clarifying the contexts in which results from the content analysis were created. Further discussion is needed on how to best report these results. Different cut-offs are useful in defining multiple medicine use in different age groups. Vast majorities of users of multiple medicines were found to have unique medicine combinations. Multiple medicine use was found to be associated with morbidity and poor self-rated health across all age groups.