Kiessling took her first national title at the East German Athletics Championships in 1989. That year proved to be the peak of her career. She began by winning her first senior medal at the 1989 European Athletics Indoor Championships, taking the runner-up spot behind Romania's Doina Melinte. The following month she recorded a lifetime indoor best of 1:59.68 minutes at the 1989 IAAF World Indoor Championships – this brought her the bronze medal as the top three all finished within half a second, beaten only by her compatriot Christine Wachtel and Soviet runner Tatyana Grebenchuk. In the outdoor season she set three further lifetime bests: 1:59.41 minutes for the 800 m, 4:04.44 minutes for the 1500 m and 8:46.99 minutes for the 3000 metres. Her 1500 m best, recorded in East Berlin, ranked her seventh in the world on time that season. She was the fourth-place finisher at the European Cup (1500 m) and 1989 IAAF World Cup (3000 m).