Objective This aim of this study was to understand the distribution of pretreatment serum LDH in NPC of each radiotherapy-related typing,and its relationship with prognosis.Methods We collected the pretreatment data of LDH in 2 665 newly diagnosed NPC who underwent radical radiotherapy between January 1,2000 and December 31,2005 at Sun Yat-sen University Cancer Center.Pretreatment serum LDH levels and survival analysis were analyzed in four kinds of radiotherapy-related typing of NPC.Results Distribution of radiotherapy-related types of 2 665 NPC were 74.6％ (1 987 cases),15.1％ (404 cases),8.6％ (229 cases),1.7％ (45 cases) for Types Ⅰ (no primary and regional recurrence and no distant metastasis),Ⅱ (primary or regional and no distant metastasis),ⅢⅡ (no primary and regional recurrence,and distant metastasis),Ⅳ (primary or regional recurrence,and distant metastasis),respectively.Increased LDH patients Ⅰ,Ⅱ,Ⅲ,Ⅳ-type proportion were:9.6％ (191/1 987),15.8％ (64/404),18.8％ (43/229),35.6％ (16/45).274 cases of type Ⅲ and Ⅳ,there were 81 cases of liver metastasis,which increased LDH levels in 34 cases,accounted for 42％.Total follow-up rate was 95.2％.The OS,LRFS,and DMFS curves for the increased LDH level group and the normal LDH level group was significant (P =0.000,0.000,0.000).Further analysis showed that the above main difference caused by the type Ⅱ (P =0.000).Conclusions Pretreatment levels of serum LDH are associated with radiotherapyrelated typing of NPC,particularly associated with type Ⅲ and type Ⅳ liver metastasis.And mainly type Ⅱ has poor prognosis.