The menstrual cycle is an integral part of human life yet much about it is not understood, including if and how it affects behavior and cognition. By studying these aspects, we can gain important knowledge into how the menstrual cycle may influence results of other psychological studies. The reason many researchers believe behavior and cognition might change across the cycle is related to evolutionary theory, specifically that during ovulation women would have better fitness if they could select a good partner. This study examines whether the menstrual cycle can affect women’s ability to detect lies. This ability could better enable women to choose an honest, long-term partner, increasing their offspring’s chances of survival and success as having a second parent present could give them more security. Thirty six participants were presented with videos and asked to determine if the video subjects were lying or telling the truth. They were also asked to give general information about their cycle to determine if each woman was a potential ovulator. No significant results were found between lie detection and ovulation. Future studies should include a larger sample size to increase validity.