background and objectives: tricyclic antidepressants (tcas) are widely used as analgesics in chronic lumbar pain and neuropathic pain. the objective of this study was to evaluate the electrocardiographic changes in patients with chronic pain treated with amitriptyline or imipramine. methods: forty patients, ages 26 to 81 years (57.27 ± 13.65 years) of both genders (female 19, male 21), with neuropathic syndromes (lumbosciatalgia, postlaminectomy syndromes, and post-herpetic neuritis, among others) participated in this study; 60% had cardiovascular diseases; 30% had changes in the ecg (rbbb, lbbb, first-degree avb, lahb, or pvcs). three ecgs were done in each patient: one ecg was done before beginning treatment, and 30 and 60 days after beginning treatment evaluating pr, qrs, qt, qtc, dqt, dqtc, and hr. thirty-two patients were on amitriptyline and eight on imipramine. the mean dose at the end of the study was 54.29 mg of amitriptyline and 46.87 mg of imipramine. results: analysis of electrocardiographic parameters after the use of tcas showed that amitriptyline caused a transitory increase in heart rate in females (p = 0.049), and the duration of the qrs in patients 60 years or older and patients with cardiopathies (p = 0.01). in patients who received 75 mg of amitriptyline, the qtc interval was greater when compared to that of patients who received 25 mg of the drug (p = 0.0044). the increase in those parameters demonstrated the effects of amitriptyline on cardiac conduction; however, clinical compromise was not seen, since they remained within normal limits (qrs < 110 msec and qtc < 470 msec). conclusions: the chronic use of tacs proved to be safe and effective, and it did not show changes in cardiac conduction with clinical repercussion.