The aim of this study was to standardize the recording technique of the SERVO MED Ep 1C to determine the rest time required for human subjects to obtain stabilized values of transepidermal water loss (TEWL). Measurements of TEWL were performed on the flexor side of the forearm in healthy volunteers. First, different sites were tested on different days to study intra- and inter-individual variations. The recordings were carried out every 5 min for 2 h. Values reached a linear state after 15 min of rest. A time-course type curve of TEWL was established.