The electroencephalogram (EEG) is a promising measure in the field of neurotoxicology. It can be well quantified by techniques which can be interpreted both physically and statistically. Such quantification schemes are briefly discussed in this paper. However, the quantification of EEG is not trivial in either the mathematical or computational sense. The relationship of EEG to brain function or brain pathology is not very well understood by some standards, perhaps due to poor quantitiative methods or erroneous assumptions about brain-behavior relationships. EEG has a similar appearance across species. Hence the measure has great promise as a cross species indicator of neurotoxicity. Not many quantitatively sound neurotoxicological studies using EEG have been published. It must be strongly emphasized that (a) more methods development is needed before the promise of cross species generality can be realized and (b) naive and/or halfhearted attempts to use this measure are perilous.