In the recent years, increasingly more attention has been dedicated to the problem of groundwater pollution by nitrates. Increased nitrate concentration in groundwater can often be found in areas with intensive agricultural production, which has been recognized as one of the most significant causes of groundwater pollution by nitrates. In Croatia, the limit value of nitrates in groundwater is determined as 50 mg L-1 by the Ordinance on Sanitary Quality of Drinking Water, which is also the limit value proscribed by the EU Nitrate Directive. This thesis examined the influence of agriculture on the nitrate pollution of surface water and groundwater in the examined area. The thesis determined the link between various cultivation methods in crop production and the sources of pollution in livestock production and the nitrate concentration in water resources. On the basis of the acquired statistical data it can be concluded that the agricultural production in the area of the Samobor-Zaprešić aquifer has no statistically significant influence on the concentration of nitrates in the surface water and the groundwater in the examined area. There are several possible explanations for the results. The sampling was not conducted with the goal of determining the impact of agriculture on the quality of water and its dynamics was not defined; to determine the impact of agriculture it is necessary to monitor the agrotechnical measures (fertilization) implemented in a certain area and to conduct the sampling accordingly. Besides, the sampling in the monitoring process was aimed towards drinking water, and it was observed that the measuring stations were grouped in the vicinity of water wells, and further away from agricultural areas (most of the monitoring was conducted on a parcel defined as a mosaic). Also, the Samobor-Zaprešić aquifer is recharged by the water from the Sava River when the water level is high, which also causes the dilution of water pollutants. The structure of agricultural production is changeable, and with it the agrotechnical measures implemented, so a research directed towards determining the impact of agriculture should be defined according to the conditions of the area of interest.