BACKGROUND: The development of so-called "Point-of-care" (POC) devices for blood or urine analysis has resulted in many systems that are widely used at home or at the bedside. We evaluated the performance of the I-STAT portable clinical analyzer for measuring blood gases (pH, PCO2, PO2) and whole blood electrolytes (sodium, potassium and ionized calcium) with reference to a conventional blood gas analyzer (Chiron 348 pH/ blood gas/electrolytes). METHODS: Thirty samples from the arterial blood were simultaneously analyzed with I-STAT system and with Chiron 348 pH/blood gas/ electrolytes analyzer. Differences between results of two methods were analyzed by paired t-test (p<0.05). RESULTS: PO2, PCO2 and Na measured with I-STAT system and Chiron 348 PH/ blood gas/ electrolytes analyzer showed no significant differences. pH, calculated HCO3, K and Ca measured by two methods showed significant difference, but observed differences would not affect clinical decisions except ionized calcium. CONCLUSIONS: This study shows that blood gas and electrolyte analysis using the I-STAT portable device is comparable with that performed by a conventional Chiron 348 pH/blood gas/ electrolytes analyzer except ionized calcium.