[Determination of trace elements in the hair: significance and limitations]. 
Trace elements analysis in hair is sometimes used by clinician for a diagnosis of nutritional deficiency.  Hair contents are supposed to reflect the elements status on an extended period.  Hair may be contaminated by environment and its mineral composition may be modified in the different steps of the analytical process.  Experiments in well known physiological conditions show a wide variability of the analytical results.  These results are poorly correlated to the nutritional status so their interpretation is difficult.  An epidemiological use of samples obtained from a wide population may provide worthwhile informations to the clinician.  It is necessary to be very careful interpreting results coming from isolated samples.