As of the end of June 2005, 27 of 96 dialysis outpatients at our clinic had developed carpal tunnel syndrome (CTS). Of 19 patients who had undergone dialysis for 30 years or longer, 15 had CTS, whereas none of the 38 patients who had received dialysis for less than 10 years had CTS. These data reflect trends in CTS development: from 1983 the incidence of CTS increased for many years, but more recently there has been a decline in new cases of CTS. Comparison of the 27 CTS and 69 non-CTS dialysis patients at our clinic showed that those in the CTS group were older and had a longer duration of dialysis. Patients in the CTS group were found to have had a high plasma beta2-microglobulin (BMG) level in the distant past (15-21 years ago), but conversely had a much lower BMG level in recent years. Simple correlation analysis and multiple logistic regression analysis showed that the presence of CTS was correlated with high BMG levels in the distant past, in addition to age and duration of dialysis. These findings suggest that reduction of the plasma BMG level due to advances in dialysis therapy in recent years has contributed to the decreased incidence of CTS.