This study investigated the impact of emotional valence on event-based prospective memory performance in depression. Thirty individuals with depression and 29 healthy adults performed a prospective memory task in which the emotional valence of the prospective targets was manipulated (positive, neutral, negative). Collapsed across all valence conditions, healthy adults outperformed individuals with depression in the prospective memory task. This effect was qualified by planned contrasts indicating that the two groups only differed when responding to positively valenced cues, reflecting a positivity effect in healthy adults. These data are in line with previous research, which shows that healthy participants better remember positively valenced cues, but are the first to show an absence of this effect in those with depression.