Two pharmacokinetic parameters viz. the minimum serum concentration in the dosage interval and the area under the serum concentration curve have been correlated to 14 parameters for clinical outcome, viz. total points and factor points from the three rating scales, BPRS, CPRS, and side effects scale, in a double blind clinical trial of clopenthixol and flupenthixol depot preparations in outpatient schizophrenics.No statistically significant correlations were observed. It is of some interest, however, that the results suggest that the treatment of individual patients with neuroleptics may be adjusted by means of repeated ratings, residual percentage, changes in psychopathology, and determinations of serum concentrations.Our results do not indicate any optimal concentration range for these depot neuroleptics in the maintenance phase of schizophrenia. The so‐called therapeutic window as to neuroleptics obviously varies with regard to the phase of the disease as well as the patients' social situatio