Introduction: In Mexico, according to the latest data from the Ministry of Health, there are between 5,000 and 6,000 new cases of cancer in children under 18 years of age, with leukaemias in more than 50%, with an approximate survival of 56% at the time of diagnosis, however in developed countries can reach up to 90%. Mexico has an annual average of 2,150 deaths from childhood cancer in the last decade according to figures from the Statistical Epidemiological System of Deaths (SEED). The main complications of these patients are when they present infectious processes, chemotherapy and immunosuppression presented throughout their treatment make them high points for research, new topics and proposals in the treatment during the last years have made the Medical advances change the prognosis and increase the survival. Many acute phase reactants have been studied as part of the initial approach and follow-up of patients during the process of neutropenia and fever, so much so that they have been included in global assessment scales as predictive factors to the response to treatment. Starting with studies such as the one presented below is of the utmost importance to justify the priority in their approach. Another problem found in these patients is when choosing which antibiotic is the best, multidrug resistance secondary to the indiscriminate use of antibiotics have recently caused problems, that is why we have had to continue investigating which are the main etiological agents found at the Naval Medical Center to be able to propose antibiotic treatments reducing this problem. Objective: We present a review article where we will observe the main mechanism by which treating these patients is so important. Information for first contact physicians; who receive these patients in an emergency service and in many cases do not know how to approach them. Always leave in the patient is immunocompromised and that the hours are important so that the delay of the treatment is an important point for the survival of the same. Conclusion: Fever and neutropenia (FN) in pediatric patients has been a problem in recent years, perhaps a world which many are unaware of, it is always important to start with the patient being in an immunosuppressed state and we as a physician having a broad vision What are the etiological agents involved in these cases will result in the importance of knowing how to treat them. Sometimes it is important to start from a simple antibiotic scheme, but we must take into account that the epidemiology is different between a hospital center and another.
