A previous study demonstrated suppression of erythropoietin production in patients treated with long-term theophylline. This effect could exacerbate anemia of prematurity in neonates receiving this drug for apnea of prematurity. In this pilot project we evaluated the effect of short-term theophylline administration on serum erythropoietin in healthy adults. Six subjects were given a bolus followed by a continuous infusion of theophylline targeted to achieve a serum level of at least 10 micrograms/ml, followed by oral theophylline for 36 hours. Serum erythropoietin and theophylline levels were measured before, during, and after drug infusion. Complete hemograms were performed before and after completion of the infusion. No significant changes in serum erythropoietin levels were seen at any time (F = 1.57, p = 0.12). Hematologic values also remained unaltered. We conclude that short-term administration of theophylline is unlikely to have any effect on serum erythropoietin levels in healthy adults.