Conversational agents are becoming more widespread in computer technologies but there has been little research in how humans interact with them. Two eye tracking studies investigated how humans distribute eye gaze towards conversational agents in complex tutoring systems. In Study 1, participants interacted with the single-agent tutoring system AutoTutor. Fixation times showed that the agent received most attention throughout the interaction, even when display size was statistically controlled. In Study 2, participants interacted with iSTART. Fixations were on the relevant agents when these agents spoke. Both studies provided evidence that humans regard animated conversational agents as conversational partners in the communication process. Copyright © 2008 John Wiley & Sons, Ltd.