We describe our experience about the use of commercial control serums during the determination of the α-amylase and alkaline phosphatases activities on the Technicon autoanalyzer ; we show the sources of error one can make when LDH and CPK activities are measured by means of commercial kits and we expose the danger of making use of a temperature correction factor illustrated by the determination of the SGPT on the LKB 8.600 at 35°C. Preference is given to the notification of the results in mU/ml at the working temperature.