Direct curve-fitting is uncontested as the method of choice for evaluating kinetic experiments. If carried out by computer, the numerical solution of such problems is superior to customary graphical procedures in any respect. However, most programs available to date, cannot be executed by small systems. We now describe a BASIC program for desk-top microcomputers that performs linear and non-linear regression analysis of kinetic data. It may be directly applied to a number of problems common in enzyme kinetics, and is easily modified to handle further ones. The performance of the program is illustrated by some typical applications; in addition, fundamental statistical methods are discussed that allow a critical examination of the results obtained.