The present invention provides novel HIV protease inhibitors containing substituted borane, carborane or metallacarborane clusters with 6 to 12 boron atoms in each cluster. The charge of each borane, carborane or metallacarborane cluster is 0, −1 or −2. The number of borane, carborane or metallacarborane clusters in the inhibitor molecule is 1 to 9, and the carborane clusters in metallacarborane inhibitors are coordinated to transition metal atom, selected from the group containing cobalt, iron, nickel and ruthenium. In the cluster, heteroatoms can be present, such as nitrogen, phosphorus, silicon, germanium, tin and sulphur. The present invention covers pharmaceutical compositions containing these inhibitors and their use, both in vitro and in vivo. They are characterized by high effectiveness and stability.