We examined the effects of unconscious priming on temporal-interval production. In Experiment 1, participants were instructed to keep visual displays on a screen for 2500 ms intervals. Half of the displays were repeated across blocks throughout the entire experiment, and the others were newly generated from trial to trial. The displays consisted of patterns so complex that the participants could not intentionally memorize them. The results showed that significantly more time elapsed for old displays than for new displays before participants (...) indicated that a 2500 ms interval had elapsed. Experiment 2 replicated this effect and excluded an alternative account based on perceived pattern complexity. The effect of repetitive presentation was obtained despite the fact the participants did not recognize the repetition, suggesting that unconscious priming increased temporal production. These results suggest that time perception is affected by an unconscious process. (shrink)