Toxocariasis is a human zoonotic infection caused by ingestion of Toxocara canis larvae or Toxocara cati larvae. Authors emphasize diagnosis difficulties of a child with hyperleukocytosis. Material and methods. Authors present a 3 year-old boy transferred in our clinic for further investigations due to leukemia suspicion. Laboratory investigations: hyperleukocytosis (WBC =104.060/mm3) with 8% eosinophils, normal immunoglobulin serum levels, negative serology for syphilis, for viral infections (Epstein-Barr, Cytomegalovirus, HIV), Toxoplasma gondii and Trichinella spiralis. Peripheral blood flowcytometry identified high number for CD4+-T lymphocytes and 5:1 ratio CD4+T cell/CD8+T cell; bone marrow aspirate shown eosinophil precursors hyperplasia (17%). Eosinophilia justified additional investigations revealing high serum titers for Toxocara canis. Stool exam revealed parasitic co-infection. Imagistic evaluation didn’t show abnormalities. Main differential diagnosis included acute and chronic leukemias. Patient received benzimidazole compounds with promptly leukocytosis improvement. Conclusions. Authors present a child with parasitic coinfections (toxocariasis, ascaridiasis, giardiasis, trichuriasis) and hematological anomaly, explaining leukemia suspicion.