A comparison of patients with lung cancer diagnosed at the University of Malaya Medical Centre, Kuala Lumpur, Malaysia from October 1991 to September 1999 with another group of lung cancer patients diagnosed at the same hospital during an earlier period of 1967-1976 was undertaken to determine whether there had been a change in the distribution of lung cancer cell types and patient demography. The number of histologically and/or cytologically proven lung cancer cases was 583 from October 1991 to September 1999 and 278 from 1967 to 1976. The mean (S.D.) age of the patients during the period 1991-1999, 60.1 (12.0) years was similar to that of patients during the period 1967-1976, 60.3 (12.2) years. There was no shift of the peak age distribution of lung cancer (i.e., the 7th decade) between the two periods. In the recent period, the percentage of patients with adenocarcinoma had increased significantly to 43.2% from 25.2% while that of large cell carcinoma had decreased to 3.3% from 11.9%. The percentages of patients with squamous cell carcinoma (SCC) and small cell lung cancer remained stable. In the period 1967-1976, SCC was the commonest cell type in men and in smokers while adenocarcinoma was the commonest cell type in women and in never smokers. In the period 1991-1999, adenocarcinoma was the commonest cell type in both men and women as well as in smokers and never smokers.