The paper introduces the **drc** package, an add-on for the R statistical software, which facilitates the simultaneous fitting of multiple non-linear regression models, particularly useful for dose-response curve analysis in bioassays. The package is designed to handle various non-linear regression models, including the logistic and Weibull models, and supports model reduction and parameter comparison across curves. The authors provide detailed examples and explanations of how to use the package, including fitting single and multiple dose-response curves, comparing parameters, and handling data with hormesis. The **drc** package offers a comprehensive set of functions for model fitting, parameter estimation, and statistical testing, making it a valuable tool for researchers in fields such as toxicology, pharmacology, and herbicide research.The paper introduces the **drc** package, an add-on for the R statistical software, which facilitates the simultaneous fitting of multiple non-linear regression models, particularly useful for dose-response curve analysis in bioassays. The package is designed to handle various non-linear regression models, including the logistic and Weibull models, and supports model reduction and parameter comparison across curves. The authors provide detailed examples and explanations of how to use the package, including fitting single and multiple dose-response curves, comparing parameters, and handling data with hormesis. The **drc** package offers a comprehensive set of functions for model fitting, parameter estimation, and statistical testing, making it a valuable tool for researchers in fields such as toxicology, pharmacology, and herbicide research.