Metoclopramide is an antiemetic drug; the effects on CNS (acute dystonic reaction, tardive dyskinesia, parkinsonism) occur in only 1 of 500 patients treated. Acute dystonic reactions are not apparently dose-dependent and suggest individual sensitivity to the drug (idiosyncrasia). We report 4 cases in 2 families (grandmother-grandchild; brother-sister). We feel that, if there is a case of dystonic reaction to metoclopramide, this drug should not be administered to other members of the same family.