Optimum design of prestressed plates subjected to multiple load conditions is formulated as a mathematical programming problem. Design variables represent plate thickness, prestressing forces, and configuration and location of tendons. Using the method of equivalent load for analysis, all the constraints are expressed explicitly as functions of the variables. Based on a transformation of variables, the design problem for a given tendon configuration or tendon location is formulated with linear constraints. In the design for minimum plate thickness or minimum prestressing forces the objective function is transformed into a linear form and the problem is reduced to linear programming. Numerical examples demonstrate the application of this method.