This paper reviews and compares existing theories for the analysis of perforated plates with holes arranged in equilateral triangular patterns.A search of recent literature reveals that three methods are available for the solution of flat perforated steel plates.All three methods are based on the assumption that a set of equivalent elastic constants can be determined, and that such constants when used in conjunction with the classical solid plate theory will completely describe its deflection and stress patterns. This paper also presents a modification which applies to two of the three existing theories.This modification improves the agreement between theory and available test results.