This paper presents a new software, Pk-fit, to fit nonlinear models to kinetic and dynamic data. Directly connected to the spreadsheet, a statistical software component manager is available. In the data manager, Pk-fit includes the noncompartmental analysis module, the compartmental analysis module, the nonlinear kinetic process module, the drug absorption module, the pharmacodynamic data modeling module, the simultaneous fitting module, and the user-defined library module. In this paper, we present a detailed comparison of the kinetic analysis using Pk-fit and common software packages, PCNONLIN, MODFIT, MKMODEL, NONMEM, and SIPHAR, based on the textbook published by Gabrielsson in 1992, "Compilation of Analyzed Data Sets for Pharmacokinetic Software Evaluation." The comparison of Pk-fit with the reference softwares revealed that the parameters and their dispersion found with Pk-fit are consistent with the ones estimated with the other programs. In conclusion, Pk-fit constituted a valid tool for pharmacokinetic/pharmacodynamic data analysis.