Frailty causes disability and restrictions on older people's ability to engage in leisure activities and for social participation. The objective of this study was to evaluate the effects of a 1-year case management intervention for frail older people living at home in Sweden in terms of social participation and leisure activities. The study was a randomised controlled trial with repeated follow-ups. The sample (n = 153) was consecutively and randomly assigned to intervention (n = 80) or control groups (n = 73). The intervention group received monthly home visits over the course of a year by nurses and physiotherapists working as case managers, using a multifactorial preventive approach. Data collections on social participation, leisure activities and rating of important leisure activities were performed at baseline, 3, 6, 9 and 12 months, with recruitment between October 2006 and April 2011. The results did not show any differences in favour of the intervention on social participation. However, the intervention group performed leisure activities in general, and important physical leisure activities, to a greater extent than the control group at the 3-month follow-up (median 13 vs. 11, P = 0.034 and median 3 vs. 3, P = 0.031 respectively). A statistically significantly greater proportion of participants from the intervention group had an increased or unchanged number of important social leisure activities that they performed for the periods from baseline to 3 months (93.2% vs. 75.4%, OR = 4.48, 95% CI: 1.37-14.58). Even though statistically significant findings in favour of the intervention were found, more research on activity-focused case management interventions is needed to achieve clear effects on social participation and leisure activities.