From a total of 2,562 cases treated by ECT during an 8-year period, 25 cases of lung abscess were discovered concurrently with or shortly after treatment. These records were reviewed in an effort to clarify the etiology. All other lung abscesses occurring during that same period were also reviewed for comparison. Of the 25 abscesses that occurred in connection with ECT, 5 deaths resulted and 10 cases retained residual pulmonary signs as compared with 3 deaths due to or associated with ECT from other causes and 20 other serious complications during this same period. The results were compared according to age, sex, length of hospitalization, diagnosis, behavior classification, technique of administering ECT, number of treatments, and time interval between last ECT and development of abscess as well as location of abscess.Abstract Teaser