We report the characterization of the env gene of a feline immunodeficiency virus isolate from France (FIV Wo). FIV Wo gag and env genes were cloned directly from cat peripheral blood mononuclear cells, using polymerase chain reaction. The env molecular clone was shown to be functional and to express antigenically relevant envelope glycoproteins in vitro. Alignment of FIV Wo sequences with available FIV sequences and application of a regionalization algorithm resulted in delineation of variable and conserved domains of FIV Env. These data were used to build a schematic folding model of FIV envelope glycoproteins. The Env molecular clone, variability map, and structural model constitute helpful tools for future studies of FIV envelope aimed at the determination of structure-function relationships or design of diagnostics or vaccine reagents.