Background The practice of maternal kissing of minor injuries of childhood (boo‐boos), though widely endorsed and practised, has never been demonstrated to be of benefit to children.

Objective To determine the efficacy, if any, of maternal kissing of boo‐boos in toddlers.

Design Randomized, controlled and double‐blinded study of children with experimentally induced minor injuries. Control arms included both no intervention group and ‘sham’ (non‐maternal) kissing. Children were blinded to the identity of the kisser in both the maternal and sham control groups.

Setting Outpatient research clinics in Ottawa, Canada.

Participants 943 maternal–toddler pairs recruited from the community.

Measurements Toddler Discomfort Index (TDI) pre‐injury, 1 and 5 minutes post‐injury.

Results One‐minute and 5‐minute TDI scores did not differ significantly between the maternal and sham kiss groups. Both of these groups had significantly higher TDI scores at 5 minutes compared to the no intervention group.