Decreased acylcarnitine levels have been found in cord blood of CF infants compared to siblings and controls. We therefore measured carnitine metabolites in blood and urine in 15 newly diagnosed (average age 4 mos) CF infants and followed the levels for one year. No consistent abnormality in carnitine status was detected in newly diagnosed infants; levels normalized at one year after therapy with predigested formula containing carnitine supplements. This data does not provide support for a primary abnormality of carnitine metabolism in CF.