El síndrome nefrótico es una enfermedad crónica relativamente frecuente en niños, siendo la peritonitis bacteriana una de las complicaciones médicas más severas. A continuación presentamos el caso de un niño de 1 año de edad que es llevado al servicio de emergencias del Hospital Nacional de Niños “Dr. Carlos Sáenz Herrera”, debido a síntomas y signos abdominales que indicaban la presencia de abdomen agudo; posteriormente se logra demostrar la presencia de peritonitis bacteriana espontánea asociada a síndrome nefrótico. Nephrotic syndrome is a relatively common chronic illness in childhood, in which a spectrum of clinical manifestations arises, such as lost of permeability of the glomerular capillary wall. One of the most severe medical complications of this disease is spontaneous bacterial peritonitis, being the main cause of death in these patients and it is very rare as an initial presentation of nephrotic syndrome. We present the case of a 1 year-old male who was taken to the National Children’s Hospital “Dr. Carlos Sáenz Herrera” emergency service. The patient manifested abdominal complaints that made him suspect of having a peritonic abdomen. He was initially diagnosed to have acalculous cholecystitis. Later, it was demonstrated that the patient was suffering from spontaneous bacterial peritonitis associated to nephrotic syndrome.