Born in Nakuru, capital of the Rift Valley Province, Benson Barus is of the Tugen ethnic group, which has also produced runners including Paul Tergat.

[2] He began to focus on road running competitions and, being managed by Italian Federico Rosa and trained by Claudio Berardelli, he ran in a number of races in Italy.

[7] Barus had a series of circuit wins in Italy in early 2002, claiming first place at the Montefortiana Turà, Corrida di San Geminiano, Trofeo Sant'Agata, Vivicittà Firenze 12K, Giro Media Blenio, and the Luzerner Stadtlauf.

[8][9][10][11][12][13] A 10K best of 27:52 minutes came at a race in Gualtieri in April 2003 and this proved to be one of the fastest runs by any athlete in the world that year.

[24][25] He made his second outing over the full distance at the JoongAng Seoul Marathon in November and recorded another sub-2:10 time, being edged into fourth place by Ethiopian Yerefu Berhanu.

[28] He completed his first half marathon under an hour to win the Udine race and his course record of 59:41 minutes ranked him as the eleventh fastest runner that year.

[34] Attempting a third straight win, he entered the Udine Half Marathon, but he had to settle for the runner-up spot behind William Chebor.