Background: The docosahexaenoic acid (DHA) intake of pregnant women is lower than estimates of the DHA accretion by the fetus, and recommendations were made to increase the DHA intake of pregnant women. Objective: The objective of this study was to determine whether the supplementation of pregnant women with DHA improved the visual acuity of infants at 4 mo. Design: We conducted a blinded assessment of a subset of healthy, full-term infants born to women enrolled in a double-blind, randomized controlled trial called the DHA for Maternal and Infant Outcomes (DOMInO) trial. Women were randomly assigned to consume DHA-rich fish-oil capsules (≈800 mg DHA/d in the treatment group) or vegetable oil capsules (control group) from midpregnancy to delivery. The primary outcome was the sweep visual evoked potential (VEP) acuity at 4 mo. The VEP latency at 4 mo was a secondary outcome. Results: Mean (±SD) VEP acuity did not differ between treatment and control groups [treatment group: 8.37 ± 2.11 cycles per degree (cpd), n = 89; control group: 8.55 ± 1.86 cpd, n = 93; P = 0.55]. VEP latencies also did not differ between groups. Irrespective of the group, maternal smoking in pregnancy was independently associated with poorer VEP acuity in the infant. Conclusions: DHA supplementation in women with singleton pregnancies does not enhance infant visual acuity in infants at 4 mo of age. Visual acuity in infancy is adversely associated with maternal smoking in pregnancy. This trial was registered at www.anzctr.org. au as ACTRN12606000327583. The DOMInO trial was registered at www.anzctr.org.au as ACTRN12605000569606.