We aimed to assess leaflet-based intervention effects on family-perceived distress, the need for improvements in professional care for delirium, and family knowledge of delirium causes.

Leaflet-based intervention effects were assessed by comparing responses of family members given in the leaflet with those of a historical control group not receiving it.

Knowledge of delirium causes was significantly more likely to be correct in the intervention group, while there were no significant differences in family-perceived distress or need for improvements in professional care for delirium between the 2 groups.

The leaflet providing information about delirium improved family knowledge of cancer delirium. To relieve family distress, a comprehensive program focused mainly on psychological aspects, in addition to educational intervention with this leaflet, is a promising strategy.