The subject invention relates to the identification of a gene involved in the elongation of polyunsaturated fatty acids containing unsaturation at the carbon 9 position (i.e., ".DELTA.9-elongase") and to uses thereof. In particular, .DELTA.9-elongase may be utilized, for example, in the conversion of linoleic acid (LA, 18:2n-6) to eicosadienoic acid (EDA, 20:2n-6). The production of dihomo-.gamma.-linolenic acid (DGLA, 20:3n-6) from eicosadienoic acid (EDA, 20:2n-6), and arachidonic acid (AA, 20:4n-6) from dihomo-.gamma.-linolenic acid (DGLA, 20:3n-6) is then catalyzed by .DELTA.8-desaturase and .DELTA.5-desaturase, respectively. AA or polyunsaturated fatty acids produced therefrom may be added to pharmaceutical compositions, nutritional compositions, animal feeds, as well as other products such as cosmetics.