In this paper we give some examples of using databases of genotoxicity and carcinogenicity for quantitative and qualitative correlation studies between short-term tests and carcinogenicity. The quality of the databases is obviously important, but one of the major deficiencies of present databases is that they are too small. Using relatively small, different databases, different results can be obtained. With small databases it is difficult to disaggregate data for homogeneous chemical classes or other types of subsets. Using the databases of Gold (carcinogenicity) and Würgler (genotoxicity), we have investigated the carcinogenic potency of genotoxic and nongenotoxic carcinogens for different chemical classes.