The present invention relates, among many things, to novel 4,5-dihydro-1H-pyrazole compounds which can be potent antagonists of the cannabis CB.sub.1 -receptor. The compounds have the formula (I) ##STR1## wherein R and R.sub.1 are the same or different and represent unsubstituted or substituted phenyl, thienyl, or pyridyl, or naphthyl. naphthyl R.sub.2 represents hydrogen, hydroxy, C.sub.1-3 -alkoxy, acetyloxy or propionyloxy, Aa represents one of the groups (i), (ii), (iii), (iv) or (v) as defined herein, Bb represents sulfonyl or carbonyl, and R.sub.3 represents benzyl, phenyl, thienyl or pyridyl, each of which is unsubstituted or substituted, or R.sub.3 represents C.sub.1-8 branched or unbranched alkyl or C.sub.3-8 cycloalkyl, or R.sub.3 represents naphthyl.