A column liquid chromatographic system for the analysis of tricyclic antidepressants in serum is described. A high separation efficiency can be obtained with a mixture of ethyl acetate, n-hexane and methylamine as eluent on a silica gel column. The retention is easily regulated by varying the concentration of n-hexane, the modifier methylamine and the water content of the ethyl acetate. Examples are given of separations of test mixtures of tricyclic antidepressants and of some of these drugs in serum. UV detection permits determinations down to the 10-ng level in serum.