THERE may be a connection between the periodicity of glacial advance and the occurrence of volcanic eruptions. Lamb1 has presented a graph which shows a similar curve for Arctic sea ice off Iceland and great Icelandic volcanic eruptions since 870 AD and Bray2 found the number of maximum advances of alpine glaciers since 1680 AD is significantly related (χ2 = 7.8, P < 0.01) to intervals with a volcanic dust veil index of 1,000 or greater. The volcanic dust estimates have now been extended to 1500 AD (ref. 1) and in this paper I analyse the relationship between these estimates and records of maximum glacial advance from 1500 AD to the present.