We have studied a new vaccine of ribosomal nature associated with glycoprotein cell walls from Klebsiella pneumoniae which served as an immunoadjuvant. Thus vaccine was administered by the aerosol route to working men free of any important disease, especially of respiratory disease. A total of 104 men working for the Commissariat à l'Energie Atomique, all volunteers, were randomly placed into two groups. During the first period, 51 patients (group I) were vaccinated three times a week during 5 weeks, and the second group was used as control. During the second period, which started on day 225, the control group received the vaccine, and the first group was revaccinated. Results of this experience show a significant difference in the immunity of the two groups. The specific antibodies increased with vaccination as illustrated by chi-square test (Yates correction), which corresponds to an independent probability equal to 0 (P = 0.5 X 10-4).