The invention relates to a method for preserving Agaricus bisporus mushrooms, other Agaricus spp. mushrooms, or other mushrooms that lose more than 15 wt % upon blanching, wherein optionally a relatively small amount (relative to the amount of fresh mushrooms) of additional ingredients is used, comprising the following consecutive steps: (a) Inserting clean fresh mushrooms in a plastic laminate bag; (b) Subjecting the bag with mushrooms to vacuum at a pressure of about 300 mbar or less; (c) Sealing the bag while keeping the vacuum; (d) Releasing the vacuum, and (e) Treating the bag with mushrooms at a temperature of about 60° C. or more. In this way a commonly used blanching step—applied before packaging—is excluded, by virtue of which energy is saved and the taste and nutritional value is improved. Thus, the mushrooms are of excellent quality with good taste and flavor and well preserved.