Toxocariasis was diagnosed in 3 out of 22 children (14%) treated in our center with high-dose chemotherapy and autologous hematopoietic stem cell transplantation (HSCT). The patients were coming from rural areas in the southeastern Poland and did not present any clinical symptoms of toxocariasis upon admission to the hospital. Although no neurological and ophthalmological abnormalities were noticed, the atypical form of toxacariasis was diagnosed based on elevated eosinophils counts, positive serological tests, and biochemical symptoms of liver damage. The authors conclude that toxocariasis should be taken into consideration in the differential diagnosis of eosinophilia in children undergoing high-dose chemotherapy and HSCT, especially if they are coming from rural areas.