An experiment was carried out in order to study the quantitative changes in the nutrient content of plants (Coffea arabica L. cv. catuai), as function of the amounts of KC1 and K2SO4 applied to the soil. Throughout the experiment, the plants were observed for toxicity effects upon growth and development. Chlorine in the leaves increased with increasing amounts of KC1 applied to the soil. There was a relationship between high concentrations of Cl in the leaves and reduced growth, necrosis and defoliation. No injurious effects of Cl were observed for levels up to 7600 ppm for all the leaves or for levels up to 9400 ppm in the leaves from the lower third of the plant. The antagonism between K and Ca was confirmed and plants receiving KC1 had less P in the leaves than the ones which received K2SO4. In these, however, P decreased with increasing applied K2SO4. Plants receiving KCl had greater concentrations of Cu in the leaves than K2SO4 - fertilized plants. In all treatments, Cu and Zn accumulated more in the stems than in the leaves.