Interpersonal interaction performance is significantly determined by group members’ personality traits. If a group lives in long-term isolation, the influence of personality traits on interpersonal interaction performance will be even stronger. The current study identified and examined the impact of the personality traits of the personnel living at the Ukrainian Antarctic Akademik Vernadsky station (N = 35) on their interpersonal interactions during long-term Antarctic expeditions. The results show that expeditioners’ personality traits significantly determined their interpersonal interactions. However, the influence of personality traits on different areas of interactions can vary significantly among different groups of expeditioners, even sometimes in diametrically opposite directions. The main reason for this is a formed microclimate specific to each group and corresponding group norms for formal and informal relations due to significant differences in personality traits that are characteristic of different groups’ participants. We determined that eleven indicators, out of a total of 23 examined personality traits, significantly differed among expeditioners from different groups (different expeditions). The study results can be used to enable better psychological selection of Antarctic expedition participants and to provide psychological support for these individuals.