Five kinds of rapid consolidation tests were compared experimentally with the tandard 24-hr test, in connection with an increasing demand of consolidation tests of soft clays. A little difference in between the tests due to the secondary compression was observed, in which such indices as the modulus of volume compressibility, the coefficient of compressibility, the compressibility index, and the preconsolidation pressure were greater in an average for the rapid consolidation tests. In practicve, however, the differences are so little in comparison with those due to non-uniformity of actural soils, that the rapid consolidation tests may well be used with enough accuracy.