SummaryActivities of enzymes hydrolysing sucrose and starch were lowered significantly in all air‐dried soils, except some naturally arid soils, stored at room temperature by more than 20 per cent and 50 per cent respectively, compared with values for fresh soils. These reductions in activities resulted mainly from the initial drying which also appreciably reduced the numbers of viable bacteria. Activities of enzymes hydrolysing sucrose generally decreased on storage at −20° C but changes were slight over long periods. Inactivation of enzymes hydrolysing starch was greater and tended to increase with length of storage. Inactivation was due partly to the effects of freezing and thawing and was greater in dry than in moist samples of soils. Activities were changed least by storage at 4° C and a significant decrease from fresh values was found occasionally in only two of the thirteen soils. Starch‐hydrolysing activity was significantly increased in two very moist soils stored for 41 weeks, probably due to germination of a few seeds. Although different soils can differ in their storage behaviour, storage in a refrigerator is most suitable and air‐drying least suitable for subsequent assays of thes