The formerly designed method for quantitative evaluation of drug effects in rats is employed for the classification of three different neuroleptic drugs, namely sulpiride, clozapine and haloperidol. Analysis of the power density spectra as obtained from the recorded activity in the cortex, striatum and reticular core results in a ‘fingerprint’ for each drug, which is then compared to the known data on various standard drugs by means of a stepwise discriminant analysis. After cumulative dosage dose-response curves are given for single frequency bands and different brain areas. The ED50 values are close to the drug dosages applied to humans. All three neuroleptics can be differentiated from each other, but are classified very close to low dosages of chlorpromazine according to the classification rule established in an earlier paper. Relying on the overall difference of the drug’s action in comparison to placebo, a single dose-response relationship is given for each com