The aim of the study was to assess the general toxic effects of dermally applied carbaryl, based on histological and ultrastructural examinations of internal organs and to relate these effects to earlier own studies where ¹⁴C carbaryl was used for determining the pesticide penetration. The pesticide was applied in doses of 1/5 and 1/10 LD₅₀, administered to the tail skin of male Wistar rats 4 hours daily, for 4 weeks except Saturdays and Sundays. After the experiment, the animals were anaesthetized and the following organs were taken for histological study: brain, lung, heart, liver, kidney, skin from the site of exposure and skin from a place at least 2 cm distant from the exposure site. Lung, liver, kidney, heart and skin were used for ultrastructural studies. Dermal application of carbaryl resulted only in slight histological changes in skin, liver, brain and lung. Even in brain and liver, where large amounts of ¹⁴C carbaryl, compared to other organs (lung, kidney, heart), where the intensity of histologic changes was earlier stated to below. Ultrastructural changes were observed in skin, liver, lung, heart and kidney.