AIM: To explore the expressions of GST-n and telomerase activity in esophageal carcinoma and premalignant lesions and to investigate the value of endoscopic methylene blue (MB) and Lugol’s iodine double staining. METHODS: Seventy-two patients with esophagopathy were sprayed endoscopically with MB and Lugol’s iodine in proper order and the areas stained blue and brown, and the area between the blue and brown stains were obtained. Depending on the pattern of mucosal staining, biopsy specimen was obtained. GST-n and telomerase activity in specimens were examined by immunohis-tochemistry and PCR-based silver staining telomeric repeat amplification protocol, respectively. RESULTS: After MB and Lugol’s iodine staining, the area between both the colors was obtained in 64 of the 72 patients and the areas were stained blue and brown in all of the 72 patients. Association test of two simultaneous ordinal categorical data showed a correlation between the esophageal mucosal staining and the esophageal histology (P<0.005). The expression of GST-n and telomerase activity in esophageal carcinoma and premalignant lesions increased. The expression of GST-n and telomerase activity in dysplasia and carcinoma was significantly higher than that in normal epithelium (P<0.005). The expression in hyperplasia was slightly higher than that in normal epithelium. With the lesions progressing from low- to moderate- to high-grade dysplasia, the positive rate increased (P<0.025). Expression of GST-n was correlated with that of telomerase activity in dysplasia and carcinoma ((?)= 0.4831, P<0.005; (?)=0.3031, P<0.025, respectively); but there was no correlation between them in normal epithelium and hyperplasia. CONCLUSION: The expression of GST-n and telomerase may be an early event in the carcinogenesis of esophagus. They may play an induced and synergistic role with each other in the carcinogenesis of esophagus. Endoscopic MB and Lugol’s iodine double staining and detection of GST-n and telomerase activity may contribute to the early diagnosis of esophageal carcinoma. AIM: To explore the expressions of GST-n and telomerase activity in esophageal carcinoma and premalignant lesions and to investigate the value of endoscopic methylene blue (MB) and Lugol’s iodine double staining. METHODS: Seventy-two patients with esophagopathy were sprayed endoscopically with MB and Lugol’s iodine in proper order and the areas stained blue and brown, and the area between the blue and brown stains were obtained. Based on the pattern of mucosal staining, biopsy specimen was obtained. GST-n and telomerase activity in specimens were examined by immunohis-tochemistry and PCR-based silver staining telomeric repeat amplification protocol, respectively. RESULTS: After MB and Lugol’s iodine staining, the area between both the colors was obtained in 64 of the 72 patients and the areas were stained blue and brown in all of the 72 patients. Association test of two simultaneous ordinal categorical data showed a correlation between the esophageal mucosal staining and the esopha The expression of GST-n and telomerase activity in esophageal carcinoma and premalignant lesions increased. The expression of GST-n and telomerase activity in dysplasia and carcinoma was significantly higher than that in normal epithelium (P <0.005 ) The expression in hyperplasia was slightly higher than that in normal epithelium. With the progress of from low- to moderate- to high-grade dysplasia, the positive rate increased (P <0.025). Expression of GST-n was correlated with that of the telomerase activity in dysplasia and carcinoma ((?) = 0.4831, P <0.005; (?) = 0.3031, P <0.025, respectively); but there was no correlation between them in normal epithelium and hyperplasia. CONCLUSION: The expression of GST -n and telomerase may be an early event in the carcinogenesis of esophagus. They may play an induced and synergistic role with each other in the carcinogenesis of esophagus. Endoscopic MB and Lugol’s iodine double staining and detection of GST-n and telomerase activity may contribute to the early diagnosis of esophageal carcinoma.