Background: The Finnish Intervention Study to Prevent Cognitive Impairment and Disability is a randomized controlled trial that has tested the efficacy of a multidomain intervention targeting modifiable risk factors to prevent cognitive impairment/dementia. A combination of healthy diet, physical, social and cognitive activity, and management of cardiovascular risks was shown to be an effective model to promote brain health among older people. The aim of this qualitative study was to explore healthcare professionals' perceptions of facilitators and barriers to implementing this lifestyle programme into health care. Methods: Four semi-structured focus group interviews were conducted among healthcare professionals working in primary care and in non-governmental organizations (N = 27). Participants were asked to discuss their perceptions of facilitators and barriers for implementing the multidomain intervention into clinical practice. Interviews were analyzed using content analysis. Results: Barriers and facilitators described by the healthcare professionals were related to infrastructure and resources, client's personal characteristics and the lifestyle intervention itself. These main categories included several sub-categories related to knowledge, motivation, resources, individualization and collaboration. The interviewees pointed out that more education on dementia prevention is needed, the work should be coordinated efficiently, resources to provide preventive health care should be adequate and multiprofessional collaboration is needed. Conclusions: Transferring a lifestyle intervention from a trial-setting to real life requires knowledge about the factors that influence effective implementation. Identifying drivers and constraints of successful implementation helps to design and tailor future prevention programmes, increases motivation and adherence and supports system change.