Background Patients at risk of experiencing medicine-related problems do not always appear willing to participate in collaborative medication management services. Little is known about the psycho-social factors which motivate patients to participate in these services. The theory of motivated information management (TMIM) suggests that patients’ willingness to participate may be motivated by their uncertainty and worry about their medicines. Objective The objective of this study was to investigate factors which may motivate patients to participate in a collaborative medication management program. Setting Fourteen semi-structured focus group interviews held throughout Australia provided the data for the study. Eighty participants were recruited by community pharmacists. Participants were recruited into the study if they had experienced Australia’s Home Medicines Review (HMR) program or would be eligible to participate in the program because they were at risk of experiencing medicine-related problems. Methods An interview guide was developed which was informed by TMIM. Focus group data were audio-recorded, transcribed and where necessary, translated into English. Main outcome measure Qualitative data were thematically analysed to identify participants’ expectations about the outcomes of HMR and the factors which may influence these expectations. Results Participants’ most salient outcome expectancies of HMR were that it was a medication-information source which would assist them to manage their medicines. Recipients of the program held overall positive outcome expectancies, whereas nonrecipients’ expectancies varied widely. Consistent with theory, participants who expressed some worry about their medicines, generally held positive outcome expectancies and were willing to participate in HMR. Compared with younger participants, older participants (those aged >74 years) tended to engage less in their thoughts about being at risk, and consequently did not experience worry. Conclusion Worry about medicines is a key factor in motivating participants to engage in medicines information-seeking. Older persons who rely heavily on heuristics appeared less likely to worry about their medicines and willing to participate in medication management services. Age-related reduction in the motivation to participate may have important implications for medication safety. Further examination of this effect is warranted because older persons are at greatest risk of medicine related problems.