Ten children with CF in matched pairs were infused with either Intralipid or with 10% glucose on a double blind basis every other week for one year. Although statistically there was significantly greater gain in height and weight in the study year compared to the previous year only for the test group, both groups improved more than expected. Cumulative data analysis showed greater improvement for the Intralipid group (23 of a possible 45 points) compared to the glucose group (-2 points; P less than .02). This study indicates the need to better define the role of nutrition in the pathophysiology of CF. Meanwhile, it is recommended that all children with CF have plasma linoleic acid levels measured at least once yearly, and if levels are low, appropriate supplements should be given.