Sepsis, severe sepsis, and septic shock are frequently encountered and highly lethal conditions among children treated in ICU; however, no many reports on research on serum albumin levels of children under these conditions are available in literature and little is known about the relationship between serum albumin level and prognosis. In this prospective study, the author observed the levels of serum albumin of children with sepsis/severe sepsis/septic shock, and explored the relationship between serum albumin level and severity of illness or prognosis. For sepsis/severe sepsis/septic shock patients admitted to the pediatric intensive care unit (PICU) during the year 2008, serum albumin concentration in peripheral blood was examined within 24 h after admission. According to the diagnostic criteria, hypoalbuminemia was defined as serum albumin level of < 35 g/L. A total of 247 cases of sepsis/severe sepsis/septic shock children were enrolled. In the order of sepsis/severe sepsis/septic shock group, there were 143, 65 and 39 cases. Overall rate of hypoalbuminemia was 72.9% (180/247). The rate of hypoalbuminemia in children with sepsis, severe sepsis or septic shock was 59.4% (85/143), 86.2% (56/65) and 100% (39/39), respectively. The mortality of hypoalbuminemic patients in sepsis, severe sepsis and septic shock group showed significant difference (P < 0.001). The rates of hypoalbuminemia of the survived cases (69.5%) was significantly lower than that of the non-survived cases (94.1%). Pediatrics critical illness score (PCIS) and serum albumin concentration was positively correlated (P < 0.001), and the mortality was negatively correlated with serum albumin concentration (P < 0.05). Hypoalbuminemia is common among children with sepsis/severe sepsis/septic shock and serum albumin level is closely related to prognosis. Serum albumin level monitoring on the basis of PCIS scoring has important clinical prognostic significance in evaluating the prognosis of severe sepsis/septic shock patients.