The publication of European Directive 2004/23/EC in the European Parliament and in the European Council on 31 March 2004 concerning the setting of standards of quality and safety for the donation, procurement, testing, processing, preservation, storage and distribution of human cells and tissues made it obligatory for sperm banks to set up quality control systems to ensure, among other goals, the satisfactory control of all procedures carried out. The objective of the present study is to set out guidelines that will make it possible to ensure the quality of the donors and frozen specimens accepted and the homogeneity of the samples supplied by a sperm bank. For this purpose, we shall describe clear-cut criteria for the acceptance of donors and frozen sperm, taking into account both analytic variability and the biological variations to be expected in semen parameters. Furthermore, we shall show how the evaluation of the results of a frozen semen specimen, on the basis of analysing a single straw after such freezing, does not guarantee the homogeneity of all the straws. Therefore, we must design a sampling plan to take into consideration all the straws obtained from a donor. This kind of plan will depend on different parameters, such as acceptable levels of quality and the tolerable rate of straws with defective semen, and will involve certain risks, both for the sperm bank and for the client. The establishment of these acceptance control criteria for frozen specimens and for donors could be of practical use for the control of the procedures applied in the operation of a sperm bank.