Interleukin‐2 (IL‐2) production is essential for optimal mammalian immune response; therefore, a cDNA encoding IL‐2 was isolated and characterized for the endangered Florida manatee, Trichechus manatus latirostris. The manatee IL‐2 cDNA was cloned by reverse transcription/polymerase chain reaction (PCR), using primers derived from IL‐2 regions conserved among various mammalian species. Manatee IL‐2 cDNA consisted of 450 base pairs encoding a predicted product of 150 amino acid residues and displayed 87%, 82%, 79%, 78%, 75%, and 73% DNA sequence homology and 74%, 69%, 63%, 62%, 61%, and 57% amino acid sequence homology with human, pig, sheep, cow, rat, and mouse IL‐2, respectively.