Simon Katich was selected to tour Sri Lanka and Zimbabwe with the national team the following season but suffered greatly from illness, including a debilitating bout of chicken pox and subsequent health problems. However he recovered to contribute further for his state, highlighted in the 2000-2001 domestic season where he helped himself to 1282 first-class runs. He later switched from Western Australia to New South Wales where he currently lives.

Katich made his Test debut on the 2001 Ashes tour of England and following Steve Waugh's retirement in 2004, established himself in the Australian team. His best Test batting performance came against India at Sydney in January 2004, when his unbeaten 125 and 77 saved Australia the Test, series, and a decade long unbeaten record at home. Despite this, he was dropped in favor of Andrew Symonds for Australia's next Test, in Sri Lanka. He regained his place and enjoyed a good Test series in India in October 2004, and followed up with a hundred in New Zealand in March 2005. However, he had a poor Ashes tour of England later that year, and after scoring only two runs in the following two Tests (against the ICC World XI and the West Indies), was dropped from the Test side. Katich was fined during the Ashes for showing dissent to umpire Aleem Dar along with captain Ricky Ponting.