Keeping all the above facts in mind, and with consideration that the incorporation of different pharmacophores usually leads to the formation of more active compounds,13 in connection with our works on the field of drug design of CAs inhibitors, herein, we decided to synthesise a series of hitherto unknown phthalimide–hydantoin hybrids and investigate their inhibitory capability against five hCAs isozymes: the cytosolic isoforms hCA I, II, and VII as well as the secreted isoform hCA VI and trans-membrane tumour-associated isoform hCA IX (Figure 2). Here, CYP24A1 is linked to neoplasm.