Dear Editor,rnIn its latest edition, the World Health Organization (WHO) provides guidelines regarding the standardization of techniques for the measurement of sperm concentration and recommends use of a 100 μm-deep hemocytometer. However, these instructions are not always followed correctly.2 Furthermore, although hemocytometers provide more accurate and consistent results, they present several drawbacks: the chamber must be properly assembled prior to its use so as to ensure that the counts are correct and it needs to be cleaned thoroughly to remove all traces of sperm, which risks breaking the glass coverslip.