There is a high incidence of undifferentiated nasopharyngeal carcinoma (NCP) in certain populations, including Greenland Eskimos. The cancer appears to have a causal association with Epstein-Barr virus (EBV), which is regularly found in NPC epithelial cells. With the aim of developing a method of screening or facilitating early diagnosis of NPC, we used the polymerase chain reaction to examine exfoliated nasopharyngeal cells for EBV in 54 Greenland and 17 white Danish subjects, none of whom was suspected of having NPC. EBV DNA was found in 81% of Greenland and 35% of Danish subjects. These findings support the concept of EBV infection leading in most cases to a chronic carrier state. It is concluded that EBV detection in nasopharyngeal cells is not at present a suitable method for identification of individuals at increased risk of developing NPC.