Background: In hospitals, potentially harmful near misses occur daily exposing patients to adverse events and safety risks. The same applies to ambulance care, but it is unclear what the risks are and why near misses arise.

Aim: To explore registered nurses’ experiences and behaviours associated with near misses where patient safety in the ambulance service was jeopardized.

Methods: Based on critical incident technique, a retrospective and descriptive design with individual qualitative interviews was used. Ten men and five women from the Swedish ambulance service participated.

Results: Seventy-three critical incidents of near misses constituted four main areas: Drug management; Human-technology interactions; Assessment and care and Patient protection actions. Incidents were found in drug management with incorrect drug mixing and dosage. In human-technology interactions, near misses were found in handling of electrocardiography, mechanical chest compression devices and other equipment. Misjudgement and delayed treatment were found in patient assessments and care measures while patient protection actions failed in transport safety, hygiene and local area knowledge.

Conclusions: Experiencing near misses led to stress, guilt and shame. The typical behaviour in response to near misses was to immediately correct the action. Occasionally, however, the near miss was not discovered until later without causing any harm.