EF-1α protein is identified and partially purified in Drosophila. EF-1α appeares as double bands of 49 and 51 kD on SDS-polyacrylamide gel. Both are basic proteins and bind to GTP as EF-1α protein in other organisms. Polyclonal antibodies were prepared against both 49kD and 51kD protein in the rabbit. The antibodies crossreact with both Drosophila and yeast EF-1α in Drosophila Kc cells it is shown that EF-1α exists as heterogeneous forms of 49-400kD in the physiological condition.