Abstract: A spermicidal vaginal composition comprises a spermicidal-effective amount of a 1,2-benzisothiazole derivative having the general formula (I) ##STR1## wherein: X is either O or S;y is H; NO.sub.2 ; an halogen atom or an alkyl radical having from 1 to 4 carbon atoms; andR is H; a straight or branched alkyl or alkenyl radical having from 1 to 6 carbon atoms, optionally substituted by one or more hydroxyl, tertiary amino and alkoxyl groups; a cycloaliphatic radical having from 3 to 8 carbon atoms; an aryl radical optionally substituted by halogen atoms, alkyl or alkoxy radicals; an aralkyl radical optionally having the aromatic moiety substituted by halogen atoms, alkyl and alkoxyl radicals; or an acyl radical --COR' wherein R' is an alkyl group having from 1 to 4 carbon atoms or an aryl radical.