AbstractData relating to the natural moisture‐content of samples of saturated fine‐grained sediments, ranging from Devonian to Recent, are assembled and discussed. They indicate that the voids occupy volumes proportionally much greater than those shown by published figures for porosity obtained by standard displacement methods. Void‐ratio/pressure (depth) relationships and formulae devised to facilitate prediction are thus likely to need revision.The natural moisture‐content varies with the predominance of particular clay‐minerals, as well as with grading. The special cases of calcareous muds, organic muds, varves and boulder clays (tills), are discussed, together with geological implications of the further study of moisture