Forty gay male couples participated in a questionnaire study comparing relationships that partners agreed were sexually open (N = 23) and relationships that partners agreed were sexually closed (N = 17). No significant differences were found in the quality of open versus closed relationships. Almost all men (93%) said they were in love with their partner. On scales assessing degree of love and liking for the partner, men in open and closed relationships were indistinguishable. Nor did the two types of relationships differ in measures of satisfaction and commitment. It appears that sexually open and closed relationships can be equally satisfying. It has been suggested that gay male relationships typically go through predictable stages in which an initial "honeymoon" of sexual exclusivity is inevitably followed by a change to openness. Only 20% of our couples followed this pattern, however. The remaining 80% showed diverse patterns such as continued exclusivity throughout the relationship or a change from initial openness to sexual exclusivity. Men's reasons for having an open or closed relationship were diverse. Personal attitudes and values about the merits of exclusivity were an important factor. Men in open relationships also emphasized the benefits of sexual variety and personal independence. Men in closed relationships stressed their desire to avoid jealousy. Although partners' agreements about whether their relationship should be open or closed had a significant effect on their actual sexual behavior, some discrepancies were found. Most men in closed relationships had had at least one outside sexual liaison, although they reported having many fewer sex partners than men in open relationships.