Bacterial infections present a polymorphic aspect, both from the point of view of the pathogens and the pathological mechanisms involved in the infectious process. Documented data reminds of a prevalence of bacterial infections in oncological children. Analyzing information from medical literature, we are putting forward a systematic presentation of the main oncological conditions, with the type of immunodeficiency specific to each one and the most frequent pathogens encountered in every type in particular. Thus, for example, in acute leukemia and acute lymphoma, in neutropenia, the most frequent infections are caused by gram-positive and gram-negative germs, but when the immunodeficiency is cell-mediated, infections with L. Monocytogenes and Salmonella occur, and the presentation continues in detail for every individual class of oncological conditions (acute leukemia and acute lymphoma, chronic lymphocytic leukemia, multiple myeloma, hairy cell leukemia and solid tumors). In the end, we are bringing the current tendency in the emergence of bacterial infections in little oncological patients to your attention. We focused on viridans streptococci and gram-negative pathogens, such as Streptococcus maltophilia, Burkholderia cenocepacia, Achromobacter species, Alcaligenes and Stenotrophomonas maltophilia, discussing their infections at large. The analysis in question has also taken into consideration two bacterial syndromes: the infection with virulent strains of Clostridium difficile, which has emerged in the recent years, with lethal potential upon oncological patients, and pyomyositis caused by Escherichia Coli, described most often in patients with hematologic malignancies.