A fully enzymatic method for measurement of l(+)-lactate has been adapted for use with a centrifugal analyzer. The procedure is based on a two-point fixed-time kinetic approach for elimination of static interferences, and commercially available reagents are used. Specimen collection and preservation are simplified by the use of standard evacuated tubes containing sodium fluoride. Under these conditions lactate is stable for as long as seven days at 4 degrees C, and deproteinization is unnecessary. The method is extremely simple and ideally suited for emergency and routine use. Determinations may be performed on plasma or cerebrospinal fluid. Sensitivity and precision are excellent, linearity extends to 8.0 mmol/liter, and results compare well with those obtained using the manual enzymatic procedure.