Objective Professional accountability programs are designed to promote professional behaviours between co-workers and improve organisational culture. Peer messengers play a key role in professional accountability programs by providing informal feedback to hospital staff about their behaviour. Little is known about the experiences of messengers. This study examined the experiences of staff who delivered messages to peers as part of a whole-of-hospital professional accountability program called 'Ethos'. Methods Ethos messengers (EMs) across eight Australian hospitals were invited to complete an online survey. The survey consisted of 17 close-ended questions asking respondents about their experiences delivering messages to peers and their perceptions of the Ethos program. Four open-ended questions asked respondents about rewarding and challenging aspects of being a peer messenger and what they would change about the program. Results Sixty EMs provided responses to the survey (response rate, 41.4%). The majority were from nursing and medical groups (53.4%) and had delivered 1-5 messages to staff (57.7%). Time as an EM ranged from less than 3 months to more than 12 months. A majority had been an EM for more than 12 months (80%; n = 40). Most agreed they had received sufficient training for the role (90.1%; n = 48) and had the skills (90.1%; n = 48), access to support (84.9%; n = 45) and time to fulfil their responsibilities (70.0%; n = 30). Approximately a third (34.9%; n = 15) of respondents indicated that recipients were 'sometimes' or 'never' receptive to messages. Challenging aspects of the role included organising a time to talk with staff, delivering feedback effectively and communicating with peers who lacked insight and were unable to reflect on their behaviour. Conclusions Skills development for peer messengers is key to ensuring the effectiveness and sustainability of professional accountability programs. Training in how to deliver difficult information and respond to negative reactions to feedback was identified by EMs as essential to support their ongoing effectiveness in their role.