Background Although healthcare institutions receive many unsolicited compliment letters, these are not systematically conceptualised or analysed. We conceptualise compliment letters as simultaneously identifying and encouraging high-quality healthcare. We sought to identify the practices being complimented and the aims of writing these letters, and we test whether the aims vary when addressing front-line staff compared with senior management.

Methods A national sample of 1267 compliment letters was obtained from 54 English hospitals. Manual classification examined the practices reported as praiseworthy, the aims being pursued and who the letter was addressed to.

Results The practices being complimented were in the relationship (77% of letters), clinical (50%) and management (30%) domains. Across these domains, 39% of compliments focused on voluntary non-routine extra-role behaviours (eg, extra-emotional support, staying late to run an extra test). The aims of expressing gratitude were to acknowledge (80%), reward (44%) and promote (59%) the desired behaviour. Front-line staff tended to receive compliments acknowledging behaviour, while senior management received compliments asking them to reward individual staff and promoting the importance of relationship behaviours.

Conclusions Compliment letters reveal that patients value extra-role behaviour in clinical, management and especially relationship domains. However, compliment letters do more than merely identify desirable healthcare practices. By acknowledging, rewarding and promoting these practices, compliment letters can potentially contribute to healthcare services through promoting desirable behaviours and giving staff social recognition.