The aim of this study was to investigate by transmission electron microscopy the changes occurring in rat hepatocytes following administration of ethyl alcohol for 70 days, as well as to evaluate the effect of mineral water from spring 3 in Baile Tusnad balneoclimatic resort administered for 30 days after completion of ethyl alcohol administration. After 70 days of ethyl alcohol administration, lipid loading in hepatocytes and a reduction of the rough endoplasmic reticulum were observed. The smooth endoplasmic reticulum was found to be much more abundant and in some hepatocytes that contained high lipid amounts, mitochondria had rarefied matrix and cristae. At 30 days from completion of ethyl alcohol administration, the rats that drank tap water showed progressively decreasing lipid loading. Also, the smooth endoplasmic reticulum was less abundant, while the rough endoplasmic reticulum was more abundant than on day 70 of the experiment. The rats that drank mineral water from spring 3 compared to those that drank tap water over the last 30 days of the experiment had lower hepatocyte lipid loading and the rough endoplasmic reticulum was much more abundant. These ultrastructural differences in the degree of lipid loading and the ratio between the smooth and rough endoplasmic reticulum are due to the beneficial effect of mineral water from spring 3 in Baile Tusnad.