A series of sulfa-analog of hydroxyurea, derived from N-hydroxysulfamide H2NSO2NHOH, were synthesized starting from chlorosulfonyl isocyanate (CSI) and O-substituted hydroxylamines. Their antiproliferative, antiviral (in synergy with ddI), and antifungal activities have been evaluated. (C) 2001 John Wiley & Sons, Inc.