Transfer of vibratory energy across boundaries between adjacent structural components can be suitably estimated by means of statistical energy analysis. Significant parameters of the statistical energy analysis are the coupling loss factors between structural components. A coupling loss factor is related simply to the transmission efficiency across the boundary between two structural components. Thus, the assessment of the influence of fluid loading and compliant coating on the trasmission efficiency relates to the influence of fluid loading and compliant coating on the coupling loss factor. Previous estimates of the transmission efficiency are used to estimate this influence on the coupling loss factor in a simple case of two panels separated by a rib. The implications of this influence on the energy transfer between the two panels are discussed.