Luteinizing hormone (LH) is physiologically produced by the anterior pituitary gland. Male athletes may use pharmaceutical LH for doping since it increases the production of testosterone by testes. This hormone is thus on the World Anti-Doping Agency (WADA) list of substances prohibited for males. Anti-doping laboratories perform the assay of this hormone in urine and report abnormally elevated results. We observed a highly significant prevalence of abnormal results in samples taken after a boxing match. Comparison of the descriptive statistics for 426 LH values observed in boxing and other sports showed significant differences. An experimental study comparing urinary LH levels in 17 boxers before and after a match demonstrated a clear increase after the match. The same observation was made for urinary follicle stimulating hormone (FSH) in all of the eight boxers tested for this other pituitary gonadotropin. These observations have consequences for anti-doping controls, as the reference range for urinary LH levels must take into account the specificities of boxers. They also suggest consequences for the health of boxers. Although to our knowledge such observations have never been described, other pituitary disorders have been reported. Our results deserve further investigation from a medical point of view. Copyright © 2013 John Wiley & Sons, Ltd.