Background: Intensive care units, operating rooms, emergency departments, and neonatology units need rapid measurements of blood gases, electrolytes, and metabolites. These analyses can be performed in a central laboratory or at the clinic with traditional or compact cassette-type blood gas analyzers such as the epoc blood gas testing system for analyzing whole blood samples at the bedside. In this study, the performance and interchangeability of a hand-held epoc blood gas analyzer was evaluated. Methods: The analytical performance of the epoc analyzer was evaluated by determining within-and between-run precisions. The accuracy of the epoc analyzer was assessed by comparing patient results from the device with those obtained with the Siemens Rapidlab 1265 and Rapidpoint RP500 and Siemens Dimension Vista and Sysmex XE-2100 analyzers. The following parameters were measured: pH, pCO 2 , pO 2 , Hb (calc), Na + , K + , iCa 2+ , glucose, and lactate. Results: The CV% of the epoc’s between-day imprecision for the various parameters varied from 0.4 to 8.6. The within-run imprecision CV% varied from 0.6 to 5.2. The squared regression coefficient (R 2 ) between the epoc and RL1265 varied from 0.94 to 0.99, with the exception of Na + and Ca 2+ (R 2 ≥0.82). The correlation (R 2 ) of Na + and K + between epoc and Dimension Vista was 0.73 and 0.89, respectively. The correlation (R 2 ) of Hb between the epoc and the XE-2100 analyzer was 0.94. Conclusions: With most of the measured blood gas parameters, the epoc analyzer correlated well with reference techniques. The epoc analyzer is suitable for rapid measurement of the blood gases, the electrolytes, and the metabolites in the ICU.