By use of the finite-difference method of numerical analysis, a detailed numerical solution is obtained for the complete one-dimensional continuity equation, to study the transient and steady-state behavior of p-n junction diodes at moderate-to-high injection levels. The solution of the continuity equation is obtained for minority carriers in the base of a diode under the influence of drift, diffusion, and recombination. From the calculated distribution of minority carriers in the base, minority-carrier and majority-carrier currents and their components are obtained. The electric field and its components in the base are determined, and the total voltage across the diode and its components are calculated. All results are obtained for transient and steady-state conditions. The effect of variations of certain physical parameters on the diode behavior is investigated. All calculations were performed on the IBM 709 digital computer.