Desulfovibrio alaskensis G20 (formerly Desulfovibrio desulfuricans G20) is a Gram-negative mesophilic sulfatereducing bacterium (SRB), known to corrode ferrous metals and to reduce toxic radionuclides and metals such as uranium and chromium to sparingly soluble and less toxic forms. We present the 3.7-Mb genome sequence to provide insights into its physiology.