Routine supplementation with multivitamins is recommended for all patients with cystic fibrosis (CF). The purpose of this study was to investigate how well patients at a large CF clinic follow recommendations for taking multivitamins and what factors affect use. A questionnaire was developed and sent to the 150 patients actively followed at our center. Of the 80 patients who returned the survey, only 47% followed clinic recommendations. Of those patients not taking extra supplements, serum vitamin A and E levels varied widely, although most were within the normal range (vitamin A 11-87 micrograms/dL, tocopherol 0.4-2.3 mg/dL, tocopherol/cholesterol 3.0-9.6 mg/g). Only 25% of respondents had known insurance coverage for vitamins. Gender or educational level did not affect adherence; however, those with minimal pulmonary disease (forced vital capacity [FVC] greater than 70% of predicted) were more likely to take vitamins than those with moderate or severe disease (P < .05). In addition to malabsorption, poor adherence should be considered by both CF specialists and primary-care providers as a cause of low serum vitamin A and E levels, especially in patients with moderate to severe lung disease.