Schei, who started for Stadsbygd IL , made its first international appearance at the 1996 Nordic Junior World Ski Championships in Asiago . There she took 26th place over 5 km classic. The following year she won the bronze medal with the relay at the Nordic Junior World Ski Championships in Canmore . In addition, she took 11th place over 15 km freestyle and tenth place over 5 km classic. In March 1997 she made her debut in Oslo in the World Cup and achieved 12th place with the relay. In the 1997/98 season she got her first World Cup points in Lahti with 26th place over 15 km freestyle and in Meråker with third place over 5 km freestyle and first place over 10 km classic her only podium places in the Continental Cup . In the 1999/2000 season she came in the points ten times. She achieved her best individual result with fourth place in the sprint in Kitzbühel and her best overall result with 29th place in the overall World Cup. In addition, she was third with the relay in Davos . She completed her 31st and last individual World Cup race in March 2002 with the Birkebeinerrennet , which she finished in 46th place.
Since December 30, 2004 Rønnaug Schei has been married to the Norwegian cross-country skier Thomas Alsgaard .