3DADE is a Fortran computer program for evaluating a series of analytical solutions of the 3-Dimensional Advection-Dispersion Equation. The analytical solutions pertain to three-dimensional solute transport during steady unidirectional water flow in porous media with uniform transport and flow properties. The transport equation contains terms accounting for solute movement by advection and dispersion, as well as for solute retardation, first-order decay, and zero-order production. The3DADE code can be used to solve the direct problem, i.e., the concentration is calculated as a function of time and space for specified model parameters, and the indirect (inverse) problem in which the program estimates selected parameters by fitting one of the analytical solutions to specified experimental data. Transient analytical solutions are evaluated for five different transport scenarios (three boundary value problems and two initial value problems) in either a Cartesian or cylindrical coordinate system. Simple steady-state solutions are also provided for three initial value problems. The program comes with a user manual giving detailed descriptions of the different transport problems, listing the main program variables, input file formats, sample input and output files, and providing a hard copy of the FORTRAN source code.