We reviewed 528 cases of decompression sickness (DCS) resulting from altitude exposure (either aircraft or altitude chamber) during the period 1 January 1977 through 31 December 1986, and treated with hyperbaric therapy. Data collected include age, sex, date and place of origin, duty position, type of exposure, altitude, diagnosis, treatment, and result. Analysis of the data described maximum altitudes of exposure, time to onset of symptoms, diagnosis, and the treatment tables used. Significant results include an increased incidence of altitude DCS requiring hyperbaric therapy among females (relative risk for females is 4.3 times that of males), no significant difference in incidence rates between duty positions in the altitude chamber exposures reviewed, and confirmation of the efficacy of hyperbaric oxygen therapy.