The performance of surface alloying using millisecond laser pulses from Nd:YAG or Nd:glass laser has been analyzed and simulated in a reasonably comprehensive computer program. This analysis is based upon using mathematical models for laser heating of solids and several assumptions to imply safeguard boundaries as to the process performance analysis and to the predicted results. A three dimensional, circular surface on semi-infinite, half-space, uniform and constant in time is the heat source mathematical model which has been adopted as the basis of this analysis. It has been selected among several models for its prevalent features which comply with the laser source and the materials (metals) being considered. The computer program has been written in Matlab environment to perform all required calculations and process performance predictions within the scope of user requirements and implied assumptions. The program incorporates a menu-driven user interface for user interrogation and alpha-numerical and graphical output to present the predicted process parameters and alloying melt pool geometry. The mathematical analysis includes: the selection of a proper integration limit for the numerical solution of the basic integration of heat equation as this limit is significantly influenced by both laser and material properties; An optimized laser focus spot size which would produce a power intensity capable of melting to the required depth without surface evaporation; The energy consumed by the alloying element; The optimum beam traverse speed and width of the melt pool; The average alloying depth; And graphical presentation of the melt pool geometry. The program has been tested with many sample cases, ten samples have been presented in this thesis. These sample cases represent five base metals, namely, copper, iron, chromium, nickel and aluminum with ten alloying elements (i.e. two types of alloying element with each base metal). The range of pulse energy is between 5J and 10J and the range of pulse duration is between 1ms and 15ms.