The instrument used can measure lactate instantaneously by a semi-automatic method using an electrochemical-enzymatic sensor. In order to test the instrument, 3 series of measurements were carried out simultaneously by the Analyzer and by the conventional enzymatic method (Boehringer, Mannheim): "normal" plasma and "normal" blood was obtained from venous blood of healthy adults; pathological plasma, obtained by addition of a known concentration of lactate to normal plasma, was also tested. The correlation curves for these three series are reported. The coefficient r is between 0.95 and 0.98, which bears out the reliability of the measurements. Since a short period, this lactate analyzer is used in our research laboratory in obstetrics.