Very little is known about Jelinians other than they possess warp technology and are accomplished engineers. A Jelinian freighter was trapped in the Void, where, in 2377, it temporarily joined an alliance led by the USS Voyager to get the collective resources to escape the anomaly. However, the Jelinians and the Kraylor left the Alliance with Bosaal prior to the Alliance's escape. Jelinian ale is an alcoholic beverage produced by the Jelinians. (VOY: "The Void")

Although it can be inferred they were native to the Delta Quadrant, there was no actual evidence of this. The Jelinians were only mentioned, and not seen.