A general multidimensional deconvolution method is developed primarily for application to the bioavailability assessment of drugs with reversible metabolism. The proposed approach involves fitting continuous functions to the experimental data and then applying a numerical deconvolution algorithm to the fitted curves. It is shown how the method may be used to determine the rates and extends of drug absorption and presystemic formation of interconversion metabolites. The proposed method is implemented as a FORTRAN subroutine called DCVSYS for the general multidimensional deconvolution problem involving any continuous functions and as a user-friendly PC-compatible program called NDCREV for evaluating the absorption of drugs undergoing reversible metabolism. The methods and computer programs are demonstrated by application to simulated drug and metabolite concentrations for a drug with reversible metabolism.