OBJECTIVE: In term infants the relationship between visual acuity and dietary fatty acid composition is not consistent, possibly due to confounders, which were mostly neglected in the studies concerned. In the current study, therefore, the influence of the essential fatty acid status and potential confounders on the visual acuity was investigated. DESIGN: The essential fatty acid status was determined at 7 months of age in red blood cell and plasma phospholipids of breastfed and formula-fed infants, born at term. Visual acuity was measured with Teller Acuity Cards. Information about potential confounding factors was obtained during an interview and with a retrospective questionnaire. RESULTS: This study, like others, showed that the concentrations of docosahexaenoic acid (DHA, 22:6n-3) are lower in plasma and red blood cell phospolipids of formula-fed infants compared to that of breastfed infants. However, no differences in visual acuity could be found between the two groups. Moreover, no significant relationship was found between the amounts of docosahexaenoic acid in plasma and red blood cell phospholipids and the visual acuity. Although dummy (pacifier) use showed a significant positive correlation with visual acuity, it did not influence the relationship between the essential fatty acids in the infant diet and visual acuity. There was also no confounding influence of smoking habits and alcohol use during pregnancy, socioeconomic background and other potential confounders. CONCLUSIONS: At 7 months of age no influence of fatty acid status, infant diet or potential confounders on visual acuity was found.