Although the effect of emotion on episodic memory has been extensively studied recently, little is known about its effects on the content of semantic memory. The present research explores how mood influences semantic memory for word emotional content. Following the induction of mood states that varied in valence and arousal, participants rated the valence and arousal of a list of words. Ratings were obtained immediately after mood induction and two days later. The positive mood induction groups rated words as more positive and more arousing than the negative groups, in both the immediate session and the delayed session, while they only rated their mood as more positive in the immediate session. Thus, mood valence affected semantic memory for word emotional content, and the effect persisted long after mood had disappeared. In addition to and independent from the mood valence effect, a time effect showed that word arousal ratings obtained in the delayed session were higher than those in the immediate session.