Horse mackerel,Trachurus trachurus, and Atlantic mackerel, Scomber scombrus, sampled from ICES Divisions VIIIb, VIIIc and IXa were examined for their level of infestation by larvae of Anisakis simple, during 1992 and 1993 respectively. Abundance, mean intensity and prevalence have been used to analyse infestation levels. The values of these measurements are dependent on the length and age of the specimens studied, particularly in the horse mackerel and to a lesser extent in the Atlantic mackerel. This species has a lower infestation level than the horse mackerel especially in respect to a specimens with greater age and length. The abundance in horse mackerel presents significative differences between geographic zones being higher in “Galician” waters (VIIIc west + IXa north) than in the VIIIc east (Cantabrian Sea). This result casts doubt on the present definition of horse mackerel stocks. The high values of prevalence in the Atlantic mackerel of Subdivision IXa north reinforce the idea that “Galicia” is a geographic zone with an abundant population of Anisakis simplex.