Affection exchange theory and previous research suggest that affectionate behavior has stress-ameliorating effects. On this basis, we hypothesized that increasing affectionate behavior would effect improvements in physical and psychological conditions known to be exacerbated by stress. This study tested this proposition by examining the effects of increased romantic kissing on blood lipids, perceived stress, depression, and relationship satisfaction. Fifty-two healthy adults who were in marital or cohabiting romantic relationships provided self-report data for psychological outcomes and blood samples for hematological tests, and were then randomly assigned to experimental and control groups for a 6-week trial. Those in the experimental group were instructed to increase the frequency of romantic kissing in their relationships; those in the control group received no such instructions. After 6 weeks, psychological and hematological tests were repeated. Relative to the control group, the experimental group experienced improvements in perceived stress, relationship satisfaction, and total serum cholesterol.