The manned Mars-stopover mission analyzed employs two vehicles: one that transfers the stopover crew from Earth to an orbit about Mars, and one that rendezvous at Mars to return the crew to Earth. Using the total mass required on Earth parking orbit as a basis, this two-vehicle mode is compared to the "standard" single-vehicle stopover. The study is limited to transfer trajectories and flyby (pickup) trips occurring in the Mars opposition of 1973. The results show that, for a chemical (O2/H2) Earth-escape propulsion system, no significant saving in mass is available regardless of the type of pickup trajectory used. For a nuclear escape system, the mass requirements of the two-vehicle system may be as much as 35% less than the single-vehicle case, provided that an increased mission duration of about 100 days may be tolerated. Trip times as low as 250 days are available for much less mass than the singlevehicle mode; however, this duration is experienced only by the stopover crew. The pickup crew in general undergoes much longer flight times, ranging from 500 to 700 days total time. Thus, no unique advantages are seen in the two-vehicle concept, other than that mentioned for the nuclear system.