The inhibition of a newly cloned coral carbonic anhydrase (CA, EC 4.2.1.1) has been investigated with a series of sulfonamides, including some clinically used derivatives (acetazolamide, methazolamide, ethoxzolamide, dichlorophenamide, dorzolamide, brinzolamide, benzolamide, and sulpiride, or indisulam, a compound in clinical development as antitumor drug), as well as the sulfamate antiepileptic topiramate. Some simple amino-/hydrazine-/hydroxy-substituted aromatic/heterocyclic sulfonamides have also been included in the study. All types of activity have been detected, with low potency inhibitors (K(I)s in the range of 163-770nM), or with medium potency inhibitors (K(I)s in the range of 75.1-105nM), whereas ethoxzolamide, several clinically used sulfonamides and heterocyclic compounds showed stronger potency, with K(I)s in the range of 16-48.2nM. These inhibitors may be useful to better understand the physiological role of the Stylophora pistillata CA (STPCA) in corals and its involvement in biomineralisation in this era of global warming.