We reviewed 72 consecutive cases of tricyclic antidepressant (TCA) overdose (OD) admitted from the emergency ward (EW) to the ICU between 1977 and 1982. Most patients were seriously ill before ICU admission: 70% were comatose; 68% were intubated, including 61% in need of mechanical ventilation; and 30% were hypothermic. One patient died after ICU admission. ECG abnormalities were present in 37 (51%) patients in the EW. These abnormalities were associated with higher TCA plasma levels, but not with either acidosis or hypoxemia. Of 14 patients without ECG abnormalities or the need for intubation in the EW, none developed new ECG abnormalities or required ventilatory support. No patient had a late complication after transfer from the ICU, after a mean stay of 2.1 days. Late, unexpected complications in TCA OD are very rare. Our study suggests that TCA OD patients who do not have an abnormal ECG and do not require ventilatory support at the time of initial evaluation may not need ICU admission simply for intensive observation.