Because of the demonstration of the presence of the herbicide bentazone in collected rainwater, and the possible presence of some other pesticides in this matrix known from the literature, a pilot study was started concerning the presence of some polar pesticides in rainwater. During the time interval May-October 1988, six sites of Dutch National Precipitation Chemistry Network (LMR), were sampled monthly. These samples were analysed, qualitatively as well as quantitatively, for the pesticides bentazone, atrazine, simazine, metolachlor and metazachlor. Bentazone was determined with liquid chromatography, after selective sample pretreatment, with a limit of determination of 0.01 mug/l. Atrazine, simazine, metolachlor and metazachlor were determined in one run with gas chromatography with nitrogen-phosphorous (NP) detection, after liquid-liquid extraction with limits of determination of 0.01-0.02 mug/l. If one of the compounds was measured, identification took place with gas chromatography- massspectrometry.<br>