The possible relation between alpha-2-adrenoceptor function-as assessed by changes in systolic and diastolic blood pressure and heart rate, as well as level of sedation, after administration of clonidine (2.0 μg/kg, i.v.)-and length of time of alcohol dependence or duration of remission was investigated in 17 male subjects with alcohol dependence in full sustained remission. Six healthy males were used as control subjects. The clonidine-induced scores for level of sedation were found to correlate with duration of time in remission (r = 0.60; P < .02). Median split of duration of remission revealed that subjects with short-term (2 +/- 1 years) duration of remission had significantly lower scores for clonidine-induced level of sedation than the scores for both subjects with long-term (12 +/- 5 years) duration of remission (P < .004) and control subjects (P < .02). There was also a significant correlation between duration of remission and values for clonidine-induced reduction of systolic blood pressure (r = 0.51; P < .05). Results indicate an extremely long recovery period in some aspects of alpha-2-adrenoceptor function, especially for clonidine-induced increase in level of sedation, with a normalization time of 4 to 5 years.