The conditions for the identification and for a quantitative evaluation, in rabbit organs, of amitriptyline and its basic metabolites (10‐hydroxyamitriptyline, 10,11‐hydroxyamitriptyline, noramitriptyline, 10‐hydroxynoramitriptyline, and 10,11‐hydroxynoramitriptyline) are reported. After a suitable purification of organ extracts a chromatographic separation of amitriptyline and its metabolites is achieved by using thin‐layer chromatography. Quantitative colorimetric analyses of metabolites are run. Copyright © 1969 Wiley‐Liss, Inc., A Wiley Company