- Background: Hypophosphatemia and thrombocytopenia may both be independent risk factors for the development of multiple organ failure and correlate well with the severity of sepsis. In the present study we wanted to analyze the potential clinical role and prognostic significance of both early hypophosphatemia and thrombocytopenia on clinical outcomes of critically ill ICU patients with severe sepsis METHODS: We analyzed the clinical data, including the outcome of critically ill ICU patients with severe sepsis who presented during a 5 year period with early hypophosphatemia and thrombocytopenia.This study was retrospective and single centre. All clinical and laboratory data was collected from the patients' ICU and hospital electronic records. All laboratory measurements were done on admission and during the ICU stay. Results: The included patients were distributed into one of three study groups based on the presence of hypophosphatemia and/or thrombocytopenia during the first 24 hours of admission to the ICU: group 1 - early hypophosphatemia; group 2 - early hypophosphatemia and thrombocytopenia and group 3 - early thrombocytopenia . The ICU mortality rate was significantly higher in groups 2 and 3 (25.9% and 22% vs. 9.3%, respectively, P = 0.034). An APACHE II score > 27, a TISS score > 25 following the first 24 hours of ICU stay , an age higher than 70, male gender and total parenteral nutrition were independent predictors of ICU and hospital mortality in this study population. Conclusion: It may be considered that hypophosphatemia and thrombocytopenia in the early stage of sepsis, even when severe and coexisting, reflect the degree of initial illness severity of sepsis. However, further investigations need to be done for a better understanding of the potential clinical role of these features in the septic critically ill population.