Plasma beta2m has been measured frequently during long term follow-up of kidney transplanted outpatients. The ratio of beta2m/log creatinine was abnormally high in 15 patients of this series bearing a symptomatic hepatitis independently of any modification of immunodepressive drug administration schedule (azathioprine and corticoids). The true effect of azathioprine could not be isolated whereas corticotherapy modified clearly the beta2m/creatinine ratio : increase of dosage for rejection resulted in a fall of the ratio whereas fast reduction increased the ratio acting essentially on circulating beta2m level (12 cases). The beta2m/creatinine ratio was normal or occasionally diminished in the 22 patients having an uneventful clinical course. Six patients showed mixed effects of hepatitis and variation of corticoid dosage and 7 cases were too much intricated to permit a good analysis of the data.