Background: Testosterone has been implicated in suicidality in cross-sectional studies. Stress that coincides with a suicide attempt may alter androgen levels, so prospective studies are needed to exclude reverse causation. We aimed to examine the associations of plasma androgens with concurrent and future suicidality, and if present, whether these associations were mediated by a behavioral trait like reactive aggression. Methods: Baseline plasma levels of total testosterone, 5α−dihydrotestosterone, and androstenedione were determined with liquid chromatography–tandem mass spectrometry, and dehydroepiandrosterone-sulphate with a radioimmunoassay. Suicidality was assessed using the Suicidal Ideation Scale at baseline and after 2-, 4-, 6-, and 9-year follow-up. Men and women were analyzed separately, and potential confounders were considered. Results: Participants (N = 2861; 66.3% women) had a mean age of 42.0 years (range 18–65) and almost half (46.9%) fulfilled criteria for a major depressive or anxiety disorder. At baseline 13.2% of men and 11.2% of women reported current suicidal ideation. In participants who were non-suicidal at baseline, slightly more men than women reported suicidal ideation during follow-up (14.7% vs. 12.5%), whereas the reverse pattern was observed for suicide attempts (3.6% vs. 4.2%). None of the associations between androgens and current and future suicidality were significant. Limitations: Androgens were determined once, which may have been insufficient to predict suicidality over longer periods. Discussion: The lack of associations between plasma levels of androgens determined by ‘gold-standard’ laboratory methods with suicidality do not support previous cross-sectional and smaller studies in adult men and women with values within the physiological range.