Among 250 consecutive autopsies (170 males and 80 females) performed at the Institute of Pulmonology in Budapest in 1996/7, there were 132 deaths in which cancer of the lung/bronchus was deemed to be the underlying cause of death. At autopsy, six cases previously thought to be dying from lung cancer were found to have died from other diseases (false positive rate = 5%). Twelve lung cancer deaths were also found to have been missed, a false negative rate of 9%, which was similar for adenocarcinoma, squamous carcinoma, and small cell carcinoma cases. Our findings confirmed the expectation expressed earlier that death certification of lung cancer would be more accurate in an institute specializing in chest diseases, to which patients had to be fit enough to be transferred, than in two general hospitals in Budapest. Nevertheless, since most cases certified as dying from lung cancer die without the benefits available in the specialized institute, the estimated false negative and positive rates for lung cancer death certification in Hungary remain high, at an estimated 56% and 30%, respectively. The much lower autopsy rates in most other countries than in Hungary points to there being considerable inaccuracy in lung cancer mortality rates internationally.