Female menstrual cycle phases have a significant impact on the nervous system. Sex differences in cognitive abilities have been related to sex hormones, but it is more controversial. The present study we investigated the influence of the menstrual cycle and sex differences on high brain functions by measuring them with computerised psychometric tests. Our study was conducted on 25 healthy, naturally cycling females and 30 healthy males between the ages of 18 and 25 who participated voluntarily. The female participants completed three test sessions (early follicular phase, the late follicular phase, and the luteal phase). We measured sex hormone concentrations in blood samples collected three times from female and one time from male. Cognitive and motor skill tests were performed, which consisted of reaction time, decision making in stress, reasoning ability, and visual memory. In addition, the Beck Depression Inventory, State-Trait Anxiety Inventory-1 (STAI-1), and State-Trait Anxiety Inventory-2 (STAI-2) were applied to determine participants’ moods as well as their short- and longterm anxiety symptoms. Decision making in stress and visual memory were significantly increased during the luteal phase compared to the early, the late follicular phases and male. The reaction times were significantly decreased male compared to the follicular phase. The findings suggested that sex steroid hormone levels, fluctuating according to menstrual cycle phases, might have neuromodulatory effects on high brain functions.