Sixteen children whose behavior was said to become aggressive, overly active, loud, and noncompliant when ingesting sugar were tested. Sugar-free home diet was maintained and an "open" challenge to a large dose (3 g/kg) of candy bar sucrose was given. Subsequent behavior was noted by actometer, quantitative playroom observation using several standard behavioral tests, and ability to do maze drawings. No significant changes were found on the open challenge test. A slight change from baseline was noted in seven cases on three or four behavioral parameters. Five of these children agreed to a double-blind challenge test utilizing lemon-flavored slushes of sucrose, honey, tapioca starch, or aspartame, administered after a standard lunch free of sucrose. One child reacted to both sucrose and honey and another child reacted only to sucrose. These two children were challenged a second time. The child who reacted to honey again did so according to actometer readings, but this time not by Stony Brook test. To sugar, he reacted only at the 70-minute Stony Brook. The other child reacted to placebo instead of sucrose when rechallenged. The results indicate that high doses of sugar are not related to abnormal behavior. "Open" challenge was sufficient to rule out such a relationship in most instances. A repeated double-blind challenge confirmed the absence of a sugar effect in cases showing initial possibility of response.