Previous research showed that when subjects imagine fictious autobiographical events, their confidence ratings of these events increase (imagination-inflation). The size of this effect is, however, too small to offer a convincing model for the development of pseudomemories in a therapeutical context. The present study examined the imagination-inflation effect when subjects write about imagined fiction. Subjects (N = 45) rated to what extent 60 events happened in their childhood. Subsequently, 4 events with a low subjective probability, were given to subjects in the laboratory. They were instructed to imagine these 4 events as if they were true and to write about these imaginations as detailed as possible. After this instruction, new probability ratings were gathered and subjects completed some questionnaires. The written down events increased significantly more in probability, compared to control events, which indicates a reliable imagination-inflation effect. However, this effect was not related to individual differences in dissociation or fantasy proneness. The main conclusion that can be drawn from this study is that writing about fictitious events enhances subjective probability ratings.