Objective To discuss the effect of the interval between neoadjuvant therapy and surgery on downstaging for local advanced rectal cancer.Method s From May 2003 to December 2008 as earlier period,32 patients with clinical stage T3 or T4 rectal cancer received neoadjuvant therapy followed by surgery after 4 -6 weeks.From January 2009 to December 2010 as later period,21 patients with clinical stage T3 or T4 rectal cancer received neoadjuvant therapy followed by surgery after 8 weeks.Dworak classification,TNM stage and clinical outcome after surgery were compared between two group paitents.Results All patients with local advanced rectal cancer received R0 resection.No surgical complications and mortality were observed in all cases.Pathological results showed that 0 and 2 cases were Dworak classification Ⅳ,5 cases were Dworak classification Ⅲ,3 and 6 cases were Dworak classification Ⅱ and 24 and 8 cases were Dworak classification Ⅰ in earlier period and later period,respectively (x2 = 9.109,P = 0.028).The postoperative staging showed that 6 and 13 cases were ypT1N0M0,22 and 6 cases were ypT2N0M0,1 case was ypT3 N0M0,3 and 1 cases were ypT3N1 M0,respectively (x2 = 10.909,P = 0.012).There were 65.6% or 81.0% cases reserved anus in earlier period and later period,respectively(x2 = 1.468,P = 0.226).Conclusions The neoadjuvant therapy followed by surgery after 8 weeks is associated with a more significant downstaging effect for local advanced rectal cancer.However,the effect of an extended interval between neoadjuvant therapy and surgery on clinical outcome still needs further investigation.