A total of 1,048 lung cancer cases obtained from the First Affiliated Hospital of Guangzhou Medical College from 1978-94 were reviewed. According to WHO's lung cancer classification, the proportion of squamous cell carcinoma (SCC) was 54.68%, for adenocarcinoma (AC) was 32.44%, for small cell carcinoma was 5.15%, and for large cell carcinoma was 1.91%. The remainder 5.82% were adenosquamous cell carcinoma (ASCC). The data on SCC and AC obtained in this study were compared to those from a former paper and were found to be similar, except those for ASCC for which the percentage appeared to have increased. When the total number of cases collected in the 16-year period was grouped into three sub-periods (1978-84, 1985-89 and 1990-94) and then analyzed, the percentage of SCC for the three sub-periods was 68.72%, 57.99% and 38.8% respectively. On the other hand, the percentage of AC was 19.43%, 29.1% and 47.49%, for the same three sub-periods. These results showed that the rate of SCC decreased progressively during the past two decades while that of AC increased markedly and even surpassed the rate of SCC. There are statistically significant differences in trend in both carcinoma types during the subperiods (P < 0.05 for SCC and P < 0.005 for AC), thus confirming the hypothesis that there is a trend towards an increase of AC in the 16-year period. The increase of adenocarcinoma appears to be due to multiple contributing factors. Future studies of longer duration are needed to help to elucidate the relative role of these factors.