Gem-Dichlorocyclopropanes (Analog II derivatives) which demonstrate antiproliferative activity toward MCF-7 cells, in vitro and are generally not reversed by estradiol or having intrinsic estrogenicity (except the hydroxyphenyl derivative Compound 30). In general the cyclopropane compounds have the formula: ##STR1## or any pharmaceutically acceptable salt thereof. X is selected from a group consisting of hydrogen and halogen atoms. The group R.sub.1 may be a hydrogen atom, an alkyl group, an acyl group, or an arylalkyl group. The group R.sub.2 may be a hydrogen atom, an unsubstituted aryl group or a substituted aryl group. The group R.sub.3 may be a hydrogen atom, an alkyl group, a cycloalkyl group, a substituted aryl group or an unsubstituted aryl group. The group R.sub.4 may be a hydrogen atom, an unsubstituted aryl group or a substituted aryl group. The R.sub.4 is absent when R.sub.3 is a cycloalkyl group having a first position carbon and a terminal position carbon bonded to the same carbon of the cyclopropane. Further, no more than any two of R.sub.2, R.sub.3 and R.sub.4 has an aryl group.