The vertical distributions of Na and Cl in the marine atmosphere near the Bahamas were measured on five consecutive days. The aerosols were sampled isokinetically from an aircraft at 8 or 10 different altitudes between 75 and 2000 m. The weights of Na and Cl in each sample were determined by neutron activation analysis. Since the Cl/Na ratio in the aerosols was close to that in seawater, it was concluded that these elements were present as sea salt. The concentrations of Na+Cl ranged from 4--7 μg/m3 at 75 m to about 0.5 μg/m3 at 2000 m.