The study was renewed in 1993 to complete the work conducted from 1988 through 1992. Case-ascertainment, data collection, and follow-up of incident cases of ILD identified during the period 10/1/88-9/30/92 were completed. The incidence of ILDs was described. The clinical characteristics of patients with ILDs were described. The prognosis of the most common ILDs were described.