A luminol-enhanced chemiluminescence assay was used to measure light elaborated by peripheral blood polymorphonuclear leukocytes (PMNs) and by pulmonary alveolar macrophages (PAMs) from 14 healthy, normal subjects and 16 patients with sarcoidosis. Resting peripheral blood PMNs (incubated only in medium) from patients with sarcoidosis generated substantially more chemiluminescence than PMNs from normal control subjects (p = 0.002). With zymosan stimulation, greater chemiluminescence was produced by PMNs from untreated patients with sarcoidosis than from normal subjects (p less than 0.05), whereas no differences were noted with latex stimulation. Chemiluminescence for resting PAMs was not different between normal subjects and patients with sarcoidosis. However, PAMs from untreated patients with sarcoidosis had higher chemiluminescence with latex particle ingestion than PAMs from normal subjects (p less than 0.05), but no differences in PAM chemiluminescence were found when zymosan was the phagocytic particle. Increased chemiluminescence by PMNs and PAMs from patients with sarcoidosis may reflect phagocyte activation in the disease process.