An effect of vitamin and mineral supplementation on the non-verbal IQs of schoolchildren was reported by Benton and Roberts (1988). A replication study using several different verbal and non-verbal tests failed to find a significant effect on any of them. However, small, non-significant effects on two of the non-verbal tests were in the same direction as the original study. These two non-verbal tests were used in a further study in which changes in non-verbal IQ were recorded following training in non-verbal reasoning. If a variable has a systematic effect on non-verbal IQ, a positive correlation should be found between change scores obtained on different tests of non-verbal reasoning. There was a significant correlation between change scores on the two tests when the independent variable was training, but not when the independent variable was vitamin supplementation. The results do not support a vitamin supplementation effect on non-verbal IQ.