The role of adaptability and harmonius interpersonal relations on achievement of existential fullness by retirement age people was analyzed with the performed empirical study. The Existence Scale (ESK) (Längle, Orgler), S. Dukhnovsky’s method examining disharmony in interpersonal relations and the Social and Psychological Adaptation Questionnaire (C. Rogers and R. Diamond) were used. The study involved 100 employed people of retirement age (59-75 years), of which 46 women (average age was 63.6 years) and 54 men (average age was 64.9 years). Employed people of retirement age were characterized by moderate understanding of life meaning, women and men did not have significant differences in their existential fullness. Interpersonal relationships were mainly harmonious; women had a greater tendency to compromise and to control aggressive manifestations in comparison with men. Both women and men were moderately adapted to the social environment. Also, men and women showed a close link between existential fullness and retirement-age people’s tendency to adaptation, especially with regard to such characteristics as self-acceptance, acceptance of others, emotional comfort and internality. An important condition for employed retirement-age people’ existential fullness and understood life meaning was their self-confidence and positive self-attitude, friendly attitude to others and expectation of positive evaluation from them, as well as self-perception as an active subject of their activities. Adaptation and acceptance of others contributed to harmonious interpersonal relationships, and vise versa, if employed retirement-age people had harmonious relationships with others, they were better adapted. The link between harmonious interpersonal relationships and existential fullness is mainly mediated by an individual’s adaptive abilities, but this link can be direct at men. Women showed a wider range of links between harmony and adaptability, but men showed a wider range of links between harmony and existential fullness. If women tended to dominate in interpersonal relationships, demonstrating their superiority over others, they were likely to narrow their inner distance from themselves and their ability to assess a situation from the outside became worse, but their tensions decreased markedly. As for men, the role of dominance increased with age, but its effect on the existential fullness and harmony of relationships was not revealed. Women who avoided problems had increased tension and aggressive intentions, but it was unlikely to affect their existential experiences; on the contrary, as for men, problems avoiding reduced their ability to self-transcendence and freedom and was unlikely to affect the harmony of relationships with others. Women’s acceptance of others and emotional comfort were more closely linked to existential fullness in comparison with such characteristics at men.