Rotaviruses (RV) are the most common cause of acute diarrhoea in children. The course of RV in-fections may vary from a mild to a serious course of diarrhoea with significant disturbances to the water-electrolyte and acid-base homeostasis and complications requiring hospitalisation. There are known cases of postinfectious enteropathy and severe cases may involve a complete villous atrophy and temporary intolerance to lactose in the course of rotavirus infection. Opinions on the changes in the permeability of the mucous of the small intestine in the result of ongoing inflammation are largely diverse. This study presents a very rare complication of a rotavirus infection which is ascites in a 3-month infant. It seems that the pathomechanism of ascites in presented patient is very complex and affected by other factors such as nutritional disorders, including hypoproteinemia and hypoalbuminemia and immunological factors.