Three squamous cell carcinoma cell lines, YES-1, YES-2, and YES-3, were established from human esophageal carcinoma. Two cell lines, YES-1 and YES-2, were established from the surgically removed tumor and YES-3 was established from pleural effusion of the pleuritis carcinomatosa by esophageal carcinoma. These three cells not only resembled the original esophageal carcinoma tissue on microscopic examination, but also produced same tumor marker, such as SCC antigen, CEA, TPA, CA125 and CA19-9. However, the secretion patterns of tumor markers were different. The doubling times of YES-1 cells, YES-2 cells and YES-3 cells were 35.2 hours, 22.9 hours, and 61.0 hours, respectively. Chromosomal studies show that chromosomal number of YES-1 cells ranges 47 to 54 with a mode of 51, that of YES-2 cells ranges 53 to 62 with a mode of 60 and that of YES-3 cells ranges 48 to 52 with a mode of 50. These three cells grow both in serum-containing medium and in serum free medium. When YES-1, YES-2, and YES-3 cells were injected into athymic nude mice subcutaneously, they introduced tumors which resembled the original esophageal carcinoma tissue histologically. These 3 cell lines may provide useful models for the study of human esophageal carcinoma.