The invention relates to a device for the temperature monitoring of a cryopreserved biological sample, comprising a sample container (in particular a cryotube) having a holding space for holding a biological sample and comprising at least one chamber, the interior of which is not fluidically connected to the holding space and is filled only partially with an indicator substance, the melting temperature of which lies in a range of −20° C. to −140° C. In particular, the chamber can be formed by a container that is detachably or pivotably fastened to the sample container. Alternatively, the chamber is formed by a double-walled slide-on part or the holding space of the sample container is double-walled, wherein an intermediate space between the inner wall and the outer wall is partially filled with the indicator substance.