This study investigated the potential of using a computer-simulated animal in a handheld virtual pet videogame to improve children's empathy and humane attitudes. Also investigated was whether sex differences existed in children's development of empathy and humane attitudes resulting from play, as well as their feelings for a virtual pet. The results showed that after playing "Nintendogs" for 3 weeks, the participants of both sexes, on average, scored higher levels of empathy on the Bryant Empathy Index, and had higher levels of humane attitudes on the Intermediate Attitude Scale, compared to their pretest scores before they played. A statistical association also was revealed between time playing with a computer-simulated animal and improved scores in empathy and humane attitudes toward animals. The findings also showed that participants tended to form emotional attachments with their virtual pet and considered it a real pet. (Contains 1 figure and 5 tables.)