Because of the rapid growth of air travel, both cargo and passenger, the payload capacity required for future transport aircraft is too great to be accommodated by fuselages of conventional configuration (that is, single-deck, single-aisle, up to 6 seats abreast). Fuselage design philosophy was therefore re-evaluated in a recent Douglas study, and this paper reviews some of the features of that study. Factors affecting fuselage design are outlined and trends are discussed. It is concluded that the forthcoming wide, single-deck fuselage, seating up to 10 abreast, will have a potential capacity of about 550 passengers. For larger capacities, the greater efficiency of multi-deck fuselages over that of the single-deck becomes increasingly apparent on a per-passenger basis. The use of multi-deck fuselages, however, will raise new problems-particularly those of airport terminal design and passenger evacuation-but these should not prove insurmountable.