Abstract: The invention relates to bis(nitrosoureido)-polyol derivatives of general formula IB.sub.1 --A--B.sub.2 (I)whereinA stands for an open chain polyol comprising 4 to 6 carbon atoms or a six-membered cyclic polyol, andB.sub.1 and B.sub.2 being attached to two different carbon atoms of the chain A, are identical or different, and stand for a group of general formula II ##STR1## wherein X stands for a halogen atom andY and Z stand for a hydrogen atom or a nitroso group, with the restriction, that in B.sub.1 and B.sub.2 Y and Z must be different.The above compounds possess valuable cytostatic activity.

Abstract: The invention relates to 1,6-dimesyl-3,4-dimethyl-D-mannitol of the formula (I), ##STR1## wherein Ms is mesyl and Me is methyl. This compound is a potent cytostatic agent which can be used to advantage in the therapy of various tumorous diseases.1,6-Dimesyl-3,4-dimethyl-D-mannitol is prepared according to the invention by subjecting 3,4-dimethyl-D-mannitol to partial mesylation followed by acylation, and splitting off the acyl groups of the resulting compound of the general formula (III), ##STR2## wherein Ms and Me are as defined above and R is a saturated lower aliphatic group, with an acidic alcohol.