R package drfit. A somewhat outdated package of basic and easy-to-use functions for fitting dose-response curves to continuous dose-response data, calculating some (eco)toxicological parameters and plotting the results. Please consider using the more powerful and actively developed ’drc’ package. Functions that are fitted are the cumulative density function of the lognormal distribution (probit fit), of the logistic distribution (logit fit), of the weibull distribution (weibull fit) and a linear-logistic model (’linlogit’ fit), derived from the latter, which is used to describe data showing stimulation at low doses (hormesis). In addition, functions checking, plotting and retrieving dose-response data retrieved from a database accessed via ’RODBC’ are included. As an alternative to the original fitting methods, the algorithms from the ’drc’ package can be used.