Lenara Kahn was a joined Trill scientist (with the Kahn symbiont) at the Trill Science Ministry. In 2372, she and her colleagues, Hanor Pren and her brother Bejal Otner, visited Deep Space 9 to conduct field tests on a technique to create artificial wormholes. Although initial results were promising, it was found that the wormholes were unstable.
While on the station, Lenara became acquainted with Jadzia Dax. Their former hosts, Torias Dax and Nilani Kahn, had been married, and they found their past feelings for each other re-emerging. After Lenara was nearly killed on the accident aboard the USS Defiant, Jadzia voiced her willingness to resume their previous relationship, despite the cost of reassociation. However, Lenara was unwilling to accept exile from Trill society, and the two parted company. (DS9: "Rejoined")
As part of the defensive effort in the Dominion War, Kahn developed a way to seal the Bajoran wormhole without damaging it or harming the beings living within, by using a series of phase-conjugate graviton beams. The technique was put into practice in 2373 in order to stop a Jem'Hadar fleet from invading the Alpha Quadrant, but the attempt was sabotaged by a Changeling infiltrator disguised as Julian Bashir. The sabotaged beam in fact rendered the wormhole even more stable and resistant to collapse. (DS9: "In Purgatory's Shadow")