Social uses of virtual reality, such as collaborative virtual environments (CVEs), are showing significant increases in general adoption. In these CVEs, it is desirable for users to feel a high level of presence, which can increase collaboration effectiveness. This study investigated the effect of facial realism on presence in CVEs. Facial realism was implemented through including eye- and mouth-tracked facial expressions in an avatar representation. A controlled within-dyad experiment was performed, consisting of a dyadic interaction between participants in a CVE. We found no significant difference between a Static Face condition and either Eye Tracked or Full Tracked (eye- and mouth) facial expression conditions. Some individual items on the questionnaire were significant or marginally significant, suggesting some positive impact on the assessment of partner reactions in the Full Tracked condition, compared to Static Face. Participants also reported a lower feeling of correspondence between virtual experiences and their physical body in the Full Tracked and Eye Tracked conditions. Some evidence has been found that this experiment warrants repetition with changes discussed in this paper, which may yield significant differences with a higher sample size.