Copulation duration varies greatly in wolf spider species, ranging from a few seconds to several hours. In Pardosa agrestis (Araneae, Lycosidae), the most common ground dwelling spider in Central European fields, copulation typically takes more than two hours. Since long copulation is likely to entail certain costs, we address the question, “what is the function of long copulations?” We investigated the consequences of lengthy copulation in an experimental situation, where copulations either ended spontaneously, or were interrupted after 10 min, 40 min or 90 min. There was no difference in the number of offspring per female when treatments were compared and we conclude that ten minutes of copulation was sufficient to fertilize all the eggs of a female. Long copulations should therefore have other functions than securing the necessary amount of sperm for fertilization. We also found that neither the time until egg production after copulation, nor offspring size was affected by copulation duration. This suggests the lack of transfer of ejaculatory substances that would either stimulate the egg sac formation or increase the size of the spiderlings. We propose that prolonged copulations gain meaning in multiple mating situations and should play a role in sperm competition or other forms of sexual selection. The extra time may be used for copulatory courtship, or for the transfer of surplus sperm or other substances to manipulate the female's willingness to copulate with other males, or to use sperm from them. These hypotheses remain to be tested in multiple mating experiments.