Detection of ovulation is an essential step in sterility treatment. Determination of the luteinising hormone is the most reliable method, which is generally performed by serum analysis. In this study, we proved the reliability of LH analysis in urine. 44 cycles of 35 volunteers with regular ovulatory cycles were examined. From day 11 on, daily LH measurements were performed on serum and urine. Ovulation was established by ultrasound monitoring of follicular development and/or by progesterone detection in the luteal phase. The sensitivity was 89% for serum analysis and 97.5% for urine analysis. The specificity was 100% for both methods. Hence, LH detection in urine is a reliable and secure method for ovulation determination. As an advantage over serum analysis, it requires less consultations, thereby offering a less expensive and stress reduced treatment.