The study examined whether individuals with early psychosis are impaired in prospective memory (PM), that is, remembering to execute a planned intention in the future, and whether implementation intentions can improve their PM performance. Thirty participants with early psychosis and 33 healthy controls were randomly allocated to either an implementation intentions or control condition and completed a computerised event-based PM task. Participants were also administered two standardised tests of PM and an abbreviated IQ test. Results demonstrated that individuals with early psychosis showed PM deficits relative to healthy controls on the computerised PM task and on some standardised measures of PM. The PM performance of the early psychosis group benefited from forming implementation intentions. Implementation intentions was concluded to be an effective strategy for improving PM performance in individuals with early psychosis.