Previous publications resulting from this study dealt with, certain aspects of the interaction of normally incident waves with a porous structure. Madsen and White (1976a), hereafter referred to as (I), developed a semi-empirical procedure for the prediction of reflection coefficients of rough impermeable slopes. Madsen (1974) with, discussion by Kondo (1975) and Closure by Madsen (1976), collectively referred to as(ll)hereafter, developed an explicit solution for the transmission and reflection coefficients of homogeneous rectangular crib-style breakwaters. When viewing the interaction of incident waves with, a trapezoidal, multilayered breakwater as a problem of energy dissipation, the problem treated in (II) may he regarded as an idealized analysis accounting for the internal dissipation of energy within the structure, whereas (I) may be regarded as an idealized analysis of the energy dissipation on the seaward face of the breakwater, i.e., the external energy dissipation. The present paper presents a synthesis of the results obtained in (I) and (II) into an approximate procedure for the prediction of wave reflection from and transmission through trapezoidal, multilayered breakwaters. The present paper presents only the major points of the approximate procedure. Thus, extensive references to (I) and (II) are made and only the determination of the hydraulically equivalent breakwater is presented in some detail. For a presentation of the entire development of this model for the reflection and transmission characteristics of trapezoidal, multilayered breakwaters the reader is referred to Madsen and White (1975) or Madsen and White (1976b) where detailed numerical examples of the use of the procedure may also be found.