During the last decade Swedish agriculture has modernized considerably, as evidenced by increasing crop yields and declines in the amount of arable land and number of farmers. Two results of this agricultural modernization have been declining air and water quality. This paper summarizes what Swedish researchers have learned from long-term measurements of nutrient losses from agriculture and the subsequent effects on the surrounding environment. The results presented here are a collection of important findings from many Swedish research teams, including some work carried out by the authors. The conclusions can be summarized briefly as follows:•Swedish agriculture contributes about one-third of the total nitrogen emissions to air through evaporation of ammonia from the handling of manure, with subsequent effects on vegetation and acidification of soils and waters.•More than half of the ammonia deposited in Sweden originates from other northern European countries.•A complex pattern, including background and human factors, influences the leaching of nitrogen and phosphorus to water. Leaching has increased since the 1950s, although atmospheric conditions also play an important role.•Agricultural activities are only one reason for the pollution of coastal waters and the open sea surrounding Sweden. Other sources of significant pollution are atmospheric deposits, forestry, households, and urban stormwater. International understanding of the environmental problems caused by agriculture is urgently needed to ensure successful management of eutrophication. About 9 percent of the total nitrogen load and 5 percent of the total phosphorus load on the surrounding seas originate from Sweden.•There are many ways to reduce the pollution caused by agriculture. The cost-effective options include tailoring fertilizer application to soil content and crop requirements, redistributing excess manure to manure-deficient farms in other areas, and introducing “wintergreen” plants.•Before pollution from agriculture can be controlled, pollution must be understood. Without that understanding, efforts to prevent pollution may be neither helpful nor cost effective.