Objective To investigate the regularity and predictors of weight loss during concurrent chemo-radiotherapy for nasopharyngeal carcinoma patients. Methods A retrospective study was carried out on 82 patients with nasopharyngeal carcinoma ,with average age of 45 years ,who received concurrent chemoradiotherapy at the Affiliated Cancer Hospital of Guangzhou Medical University. Paired t-test was used to analyze the weight loss pattern during chemoradiotherapy. The Spearman′s rank correlation analysis was used to investigate the correlation between high weight loss(HWL)and the clinical factors. Results The paired t-test showed that the weight of the patients decreased continuously every week during chemoradiotherapy(P < 0.05),and the value dropped most significantly during the 4th week. Among these 82 patients,32 were determined as HWL(weight loss > 10%). Spearman′s rank correlation analysis showed that HWL was associated with older age,female,higher T and TNM stage,3D-CRT technology,the higher dose of radiotherapy in nasopharynx and in neck lymph node,and decreases of leukopenia and hemoglobin over degree Ⅱ(P<0.05). Conlousions Weight may decrease continuously every week during chemoradiotherapy for nasopharyngeal carcinoma patients. Age,gender,T stage,TNM stage,radio-therapy dose,and leukopenia and hemoglobin decreases may be predictors for weight loss degree during concurrent chemoradiotherapy for nasopharyngeal carcinoma patients.