Trace and heavy metal and pesticide contents of different tobacco brands sold in Finland during 1920 to 1984 were determined by atomic absorption spectroscopy and gas chromatography-mass spectrometry with the purpose of investigating the variation in contents over time. In addition, the following were studied: the effect of commercial filters in cigarettes in preventing the inhalation of metals, the transfer of metals and pesticides to the mainstream smoke; and the correlation between the cadmium content of adipose tissue of smokers and their smoking habits. No differences were found in trace and heavy metal contents of different brands and packs from different decades. The pesticide residues in tobacco have followed the pattern of their use in the tobacco plantation. The dichlorodiphenyltrichloroethane (DDT) content of tobacco has decreased during the past 20 yr to about 1/200 of the peak value, i.e., from 34.5 to 0.17 micrograms/g. Cigarette filters significantly prevent the inhalation of cadmium, lead, magnesium, and iron. The mean content of cadmium in fat tissue of male smokers was four times that of non-smokers. The difference was statistically significant.