Limited research suggests that micronutrient supplementation may have a positive effect on the academic performance and behavior of school-aged children. To determine the effect of multivitamin/mineral supplementation on academic performance, students in grades three through six (approximate age range=8 to 12 years old) were recruited from 37 parochial schools in northern New Jersey to participate in a double-blind, placebo-controlled clinical trial conducted during the 2004-2005 academic school year. Participants were randomized to receive either a standard children's multivitamin/mineral supplement (MVM) or a placebo. MVM or placebo was administered in school only during lunch or snack period by a teacher or study personnel who were blinded to group assignment. The main outcome measured was change in scores on Terra Nova, a standardized achievement test administered by the State of New Jersey, at the beginning of March 2005 compared to March 2004. Compared with placebo, participants receiving MVM supplements showed no statistically significant improvement for Terra Nova National Percentile total scores by treatment assignment or for any of the subject area scores using repeated measures analysis of variance. No significant improvements were observed in secondary end points: number of days absent from school, tardiness, or grade point average. In conclusion, the in-school daily consumption of an MVM supplement by third- through sixth-grade inner-city children did not lead to improved school performance based upon standardized testing, grade point average, and absenteeism.