The thesis examines existing taxes on pesticides in Sweden and Denmark, taxes on fertilizers in Sweden and Austria as well as the Minas system in the Netherlands. The study builds on the theory of implementation of taxes with an emphasis on the internalization of externalities. Conclusions whether the existing taxes have been efficient are based on a comparison of policies and consumption of the goods before and after tax changes. Most taxes have been effective: Swedish taxes on fertilizers and pesticides have reached their goals although consumption has increased the last years for both of them. Denmark’s tax on pesticides was very effective. The Minas system is too new to draw any reliable conclusions about, but it seems to have had some negative effect on consumption patterns. Austria’s tax on fertilizers had no larger impact on price for consumers and did not have the expected effect: therefore, an abolishment of the tax came in 1994. All cases show that the taxes, by themselves, would not have had as strong of a negative effect on consumption if they were not part of a policy package: it is also important how the government uses the revenues from these taxes.