In spite of combined oral contraceptives (COCs) having been available for more than 50 years, surprisingly little is known about the prevalence of truly COC-related adverse mood symptoms and about the underlying biological mechanisms of proposed changes in mood and affect. Precise estimates of COC-related adverse mood symptoms are not available due to the lack of placebo-controlled trials. In prospective trials the frequency of women who report deteriorated mood or deteriorated emotional well-being varies between 4 and 10%, but it can be assumed that the causal relation in these prevalence rates is overestimated. Adverse mood symptoms and somatic symptoms are most pronounced during the pill-free interval of the treatment cycles, but whether extended COC regimens would be more favorable in this respect is not known. COCs with anti-androgenic progestagens, such as drospirenone and desogestrel, appear more favorable in terms of mood symptoms than progestagens with a more androgenic profile. Available data suggest that lower doses of ethinylestradiol could be beneficial.