Tricyclic antidepressants have been reported to relieve the paresthesiae associated with peripheral neuropathies of many etiologies. We designed a randomized, double-blind, placebo-controlled, crossover trial to establish the efficacy of nortriptyline in the treatment of cis-diamminedichloroplatinum (CDDP)-induced paresthesiae. The study included 51 evaluable patients with CDDP-induced peripheral neuropathy and painful paresthesiae. The study consisted of two 4 week phases, separated by a 1 week 'wash-out' period, in which patients received escalating dosages of either placebo or nortriptyline. The target maximum dose of nortriptyline was 100 mg/day. Each patient filled out pre-randomization and then weekly questionnaires assessing paresthesiae severity, hours of sleep, quality of life, and adverse effects over the 9 week study. No significant differences in paresthesia were observed in the first treatment period between nortriptyline and placebo (means of 49 and 55 respectively on a 0-100 point scale, P=0.78). Although some evidence of a modest effect in favor of nortriptyline was observed during the second treatment period (about one patient in five got a 10-point reduction in pain from drug above placebo effect), this occurred in the presence of a strong carryover effect. Linear models analysis and Bayes methods confirmed that the effect of nortriptyline on paresthesia was modest at best. Hours of sleep increased in the nortriptyline phase (P=0.02). There was no significant difference in measures of quality of life and the effect of paresthesiae on patients' daily activities between nortriptyline and placebo. There was no major toxicity associated with nortriptyline, but dry mouth, dizziness, and constipation were more common with nortriptyline. In summary, nortriptyline failed to demonstrate strong evidence of any effect on paresthesia or pain. The presence of a potential effect which appeared in the second period of the crossover design is questionable due to the observed carryover effect. Cross-validation sensitivity analysis of results support the conclusion that nortriptyline provides modest improvement at best over placebo in terms of chemotherapy-related neuropathy.