At the 2003 World Cross Country Championships she finished eighth in the long race, while the Kenyan team, of which Kilel was a part, won the silver medal in the team competition. After having runner-up finishes at the 2003 Venice Marathon and 2004 Prague Marathon, she won her first race over the classic distance at the Palermo City Marathon, knocking over five minutes off the former course record with her time of 2:31:15. She finished sixteenth at the 2005 IAAF World Half Marathon Championships and won the Nairobi Marathon that year. In other competitions, she won the Semi-Marathon Marvejols-Mende and came seventh at the Hamburg Marathon.