Objectives: The current study evaluated the effectiveness of a form of family therapy developed in Korea. The “Thank you – Sorry – Love” (TSL) model was applied to a group of elderly retired men to improve the quality of their marriage and to reduce their stress. Methods: Thirty married retired Korean men were assigned to three groups. Group 1 received 14 sessions over 7 weeks of the TSL intervention. Group 2 received 14 sessions of educational classes related to retirement and aging. Group 3 received nothing. Assessments were made of the men’s marital quality (using the Dyadic Adjustment scale) and oxidative stress (a biological marker of health), pretreatment, posttreatment, and 5 weeks after treatment. The husbands’ wives were assessed in terms of marital quality at similar time points. Results: Husbands who received TSL therapy experienced statistically significant decreased oxidative stress (8-isoprostane levels) and increased marital quality. The spouses of the TSL program participants also showed statistically significant improvement in marital quality. The educational comparison group and no-treatment control group clients did not significantly improve on either measure, nor did their spouses experience improved marital quality. Conclusions: TSL family therapy was followed by both psychosocial (husbands and wives’) and physiological (husbands’) improvements. Additional randomized clinical trials of this promising family therapy may be warranted.