Background Sexual activity and intimacy contribute to wellbeing throughout adult life, including after a heart attack. Providing support and information about sexual activity and intimacy after a heart attack is recognised as part of a comprehensive approach to cardiac rehabilitation. Previous research shows that patients expect health professionals to initiate discussions about sexual activity and intimacy, but that this seldom occurs. Methods Drawing on qualitative survey responses from a range of Australian health professionals working in cardiac care and rehabilitation, this research examined their perspectives on discussing sexual activity and intimacy with their patients, and patients’ partners. Using a social constructionist approach, thematic analysis was used to identify themes expressed by participants. Results Discussions about sexual activity and intimacy after heart attack were perceived as nebulous and taboo. The predominance of an illness – rather than wellness – framing of these discussions and a tendency for health professionals to make judgement calls contributed to discussions not occurring. Health professionals also identified a range of intrapersonal, interpersonal and structural obstacles to discussions, including embarrassment, fear of patients’ embarrassment, a lack of role clarity, the absence of a clear protocol or training to guide practice, and a lack of time, privacy and patient resources. Conclusions Such discussions require normalisation, careful timing, sufficient time and adequate privacy. Staff training, a protocol and appropriate patient resources are needed to support health professionals to initiate discussions. Further research is required that investigates the impact of specific resources and training on health professionals’ practice and patient outcomes.