A series of novel selenides bearing benzenesulfonamide moieties was synthesized and investigated for their inhibition on six human (h) carbonic anhydrase (CA, EC 4.2.1.1) isoforms such as the physiologically relevant hCA I, II, VA, VB, VII, and IX and the X-ray complex in adduct with hCA II for some of them investigated. These enzymes are involved in a variety of diseases including glaucoma, retinitis pigmentosa, epilepsy, arthritis, metabolic disorders, and cancer. The investigated compounds showed potent inhibitory action against hCA VA, VII, and IX, in the low nanomolar range, thus making them of interest for the development of isoform-selective inhibitors and as candidates for various biomedical applications.