Piperazine derivatives of formula
and their pharmaceutically acceptable acid addition salts are disclosed. In the formula n is 1 or 2, R is hydrogen or lower alkyl, R¹ is an aryl or nitrogen containing heteroaryl radical, R² is hydrogen or lower alkyl, R³ is aryl, C₄₋₈ alkyl or aryl(lower)alkyl and X is a functionalised group of specified meaning. The compounds exhibit activity as 5-HT1A antagonists and can be used, into alia, for the treatment of CNS disorders, such as anxiety.