Excavated brick walls at Moenjodaro are deteriorating at an unacceptable high rate because of the crystallization and hydration of the mineral thenardite (sodium sulfate). Its destructive effect is mainly attributed to a volume increase of 315 percent resulting when thenardite hydrates to form sodium sulfate dehydrate. Subfloresence by soluble salts is a much more destructive process than efflorescence. Soluble salts are being carried into the brick and to their surfaces by the migration and evaporation of moisture. Possible sources of the moisture in walls are rainfall, drainage and runoff water, ground water rising by capillary action, and condensation of moisture. To reduce the rate of brick deterioration the following measures are recommended: remove soluble salts form the brick; place damp-proof courses under system. Theses and other measures are necessary even if the groundwater table can be successfully lowered. Possible uses of preservatives and consolidants to conserve brick are discussed. Treating brick with preservatives will probably not successfully protect them and may accelerate the deterioration of brick. Consolidants appear to have one possible application at Moenjodaro, which is to consolidate badly deteriorated brick, thereby delaying to a future time the need to replace them with new brick. Certain epoxies could be injected into crumbing masses of brick to improve their structural integrities. Epoxies could also be used in the making of damp-proof courses and membranes.