This research was conducted at neo-shamanic ayahuasca retreats in Brazil that were led by a transpersonal psychotherapist. 22 international (English-speaking) retreat participants completed quantitative and qualitative assessments on a confidential website using a repeated measures design. Scales of the Big Five Inventory following participation showed a decrease in Neuroticism ( p < .01) and an increase in Agreeableness (p < .05). The Washington University Sentence Completion Test (SCT) was used to measure ego level. SCT scores increased for 36% of the participants ( mean increase = 2.13), while for another 36% they decreased ( mean decrease = 1.25), and for 27%, results did not show any change. The SCT results suggest that the ayahuasca retreat facilitated growth for those whose SCT scores increased and may have indicated difficulty with integration for those whose SCT scores decreased. Thematic analysis of responses to the qualitative assessments showed that the ayahuasca retreat was, overall, a therapeutic and positive experience for the great majority of participants.