<p>While previous research has proposed the existence of hormonally sensitive subtypes in other psychopathologies, such as depression, it remains unknown whether impulsivity is a hormone-sensitive phenotype for disorders like attention-deficit/hyperactivity disorder (ADHD). The current paper offers a novel contribution by investigating this concept within a sample of women characterized by high impulsivity, specifically ADHD, as they are monitored daily across the menstrual cycle, with data collected on ADHD symptoms, trait impulsivity, and task and self-ratings of executive function. The study sample was 103 young adults, aged 18 to 25, who had regular menstrual cycles and were monitored for one month, during which phase-specific data were collected. Diagnostic and trait data was collected at an initial diagnostic visit at the beginning the cycle (mid-follicular phase), self-reported ADHD symptoms were assessed daily, while self-reported executive functioning and response inhibition and working memory tasks were evaluated over four cycle phases, namely at the mid-follicular, post-ovulatory, mid-luteal, and perimenstrual phases. Study findings suggested ADHD symptoms and cognition are worse in more impulsive women and that cycle effects appear more salient for those lower in trait impulsivity. Namely, results of the current study indicated that the midfollicular phase was risky for self reported EF deficits compared to the midluteal phase which seemed protective not just for self reported EF deficits but also inattentive symptoms. In contrast, the postovulatory period seemed particularly risky for hyperactivity symptoms. Effects were more salient at low levels of impulsivity and mainly carried by negative urgency. At lower levels of positive urgency, the midluteal phase seemed protective for working memory performance. Impulsivity, similar to negative affect or PMDD, may be a hormone-sensitive phenotype in women with ADHD.</p>