Background: There is evidence linking women's testosterone (T) to competitive behaviours in sport and exercise. To advance this work, we examined the longitudinal relationships between salivary T (sal-T) and competitiveness in athletic women who differ in training status. Methods: Elite (n = 9) and non-elite (n = 21) women athletes were monitored on days 6–8 (follicular phase), 13–15 (ovulatory phase) and 20–22 (Luteal phase) of a menstrual cycle with two repeats. Salivary T levels were assessed before breakfast, followed by two questions (each rated on a 1–7 scale) on competitive desire and training motivation. Using a linear mixed model, we evaluated the menstrual phase and training status effects on each variable, before assessing the within-subject effects of sal-T on competitiveness. Results: Salivary T concentrations were higher at ovulation (effect size [ES] difference = 0.2–1.4), relative to the follicular and luteal phases, with a more marked response among elite women (p <.01). The competitiveness ratings showed similar menstrual-phase variation (ES difference = 0.6–1.0 at ovulation). A positive effect of sal-T on competitiveness emerged in both groups (p <.001), but with different slope patterns (p <.015). Specifically, the elite sal-T relationships with desire to compete (standardized β = 1.147, SE = 0.132) and training motivation (β = 1.195, SE = 0.124) were stronger compared with non-elite women (β = 0.631, SE = 0.114; β = 0.778, SE = 0.114), respectively. Conclusions: Morning sal-T concentrations, competitive desire and training motivation all peaked around ovulation in women athletes. Notably, sal-T availability and its relationship with competitiveness was stronger among high-performing athletes. Our findings confirm menstrual fluctuations in T and competitiveness among naturally-cycling women, with population context as a moderating factor.