Aims and objectives. To explore the factors that influence the use of de-escalation and its success in halting conflict in acute psychiatric inpatient setting. Background. De-escalation is the use of verbal and nonverbal communication to reduce or eliminate aggression and violence during the escalation phase of a patient's behaviour. Although de-escalation is a first-line intervention in aggression management in acute psychiatric settings, little is known about the use or effectiveness of this technique. Design. A retrospective case note analysis. Methods. For each patient (n = 522), their involvement in conflict (e.g. aggression) or containment (e.g. coerced medication) during the first two weeks of their admission was recorded. The frequency and order of the conflict and containment events were identified during each shift. The sequences of events occurring in shifts involving de-escalation were analysed. Sequences where de-escalation ended the pattern of conflict or containment were categorised as 'successful', and all others were categorised as 'unsuccessful'. Results. Over half of patients (53%) experienced de-escalation during the first two weeks of admission, with the majority of these (37%) experiencing multiple episodes. De-escalation was successful in approximately 60% of cases. Successful de-escalations were preceded by fewer, and less aggressive, conflict events, compared with unsuccessful de-escalations, which were most frequently followed by administration of pro re nata medication. Patients with a history of violence were more likely to experience de-escalation, and it was more likely to be unsuccessful. Conclusions. De-escalation is frequently effective in halting a sequence of conflict in acute inpatient settings, but patients with a history of violence may be specifically challenging. Relevance to clinical practice. These findings provide support for de-escalation in practice but suggest that nurses may lack confidence in using the technique when the risk of violence is greater. Providing evidence-based staff training may improve staff confidence in the use of this potentially powerful technique.