Pesticides were detected in groundwater samples collected from 14 wells in the Río Vélez aquifer, Málaga. From September 1993 to September 1994, water samples v/ere collected and analyzed for determining atrazine, simazine, methidatioh, lindane, DDT, methylparation and diméthoate. The most commonly detectedpesticide was simazine (12 detections); methidation, methylparation and dimethoate were also found, although the Concentrations detected were below the ECD prescribed limit (0,1 ¡ig/l) in all the samples. The remaining pesticides were not detected. The occurrence and distribution of pesticides probably are related to the local land use near a sampling site