Introduction: Cryptic septic shock may show poor outcomes despite the setting of normal hemodynamic indices. Patients with cryptic septic shock often undergo severe tissue hypoperfusion and progressing to overt septic shock within several hours in emergency department (ED). We performed the study to compare clinical characteristics and outcomes of sepsis patients with cryptic shock, cryptic to overt shock, and overt shock. Methods: We analyzed the sepsis registry from August 2008 to March 2012 for adult patients presenting to an ED of a tertiary urban hospital and meeting the criteria for severe sepsis or septic shock. We classified enrolled patients as cryptic shock (CS) group, cryptic to overt shock (COS) group, and overt shock (OS group), defined as sepsis with a lactate ≥4 mmol/L and normotension, initially cryptic shock progressed to overt shock within 72 hours, and sepsis with overt hypotension on ED arrival, respectively. The primary outcome was inhospital mortality. Results: A total 758 patients were included. Of the eligible patients, 212 patients were assigned to the CS group, 145 patients to the COS group, and 401 patients to the OS group. There was significant difference in in-hospital mortality (9.0% in the CS group, 26.2% in the COS group, and 17.2% in the OS group, p<0.001). Compared with the OS group, adjusted odds ratio (OR) for in-hospital mortality was 0.40(95% confidence interval [CI], 0.20-0.81; p=0.011) in the CS group and 1.02(95% CI 0.57-1.85; p=0.93) in the COS group. Among patients who initially showed cryptic shock (the CS and COS group), a higher blood lactate concentration and respiratory failure were significant risk factors for progression to overt septic shock. Conclusion: Cryptic septic shock without deterioration to hypotension during initial treatment showed significantly lower mortality than overt septic shock. The mortality of cryptic septic shock, however, was comparable to overt septic shock when it progressed to apparent hypotension. Prevention and early management of hypotension are critical strategies for improving survival of patients with cryptic septic shock.