Disclosed herein are compounds of formula Ar1—X—W—Ar2 wherein Ar1 and Ar2 represent aryl groups characterized generally as aromatic heterocycles (e.g. imidazolyl or tetrazolyl) or carbocycles (e.g. phenyl or naphthalenyl); the aryl groups are optionally substituted or fused with other heterocycles or carbocycles; the aryl groups can bear substituents such as alkyl, halo or O-alkyl. X is a heteroatom, a valence bond or an optionally substituted divalent methylene, and W represents a spacer; typical spacers include divalent alkylene or alkylene-amido, -amido or -oxy radicals, which may optionally be substituted (e.g. hydroxyl or oxo). A typical compound is a derivative of 2-(N-napthalenyltetrazolylthio)-N-(2-nitrophenyl)acetamide. The compounds have inhibitory activity against Wild Type and single or double mutant strains of HIV.