Aims: To analyze the methodological design of long-term longitudinal studies of alcoholics who have undergone treatment. Methods: Systematic review of prospective longitudinal studies of treated alcoholics with follow-up periods of at least 8 years, and published in English, during the period 1983-2009. The review includes 9 studies which analyzed: follow-up evaluations, information sources, the period of reference in the final assessment, the measurement of alcohol use, the operationalization of drinking patterns, and data analysis. Results: 2434 patients (ranging between 57 and 850 per study) were studied on average for a period of 15.3 (D.T. = 3.2) years (range 8-20 years). Studies differ in the number of intermediate evaluations (0, 1, 3, 4) and the length of the period considered for the final evaluation (the whole period, the last 3 years, the last year, last 6 months, last month or present situation). Drinking patterns tend to be used as the main outcome variable, but they are operationalized in non-equivalent forms and the analysis is performed using classical cross-sectional statistical techniques. Alcoholism evolution is studied by analyzing the evolution of drinking patterns and patients¿ life situation during the period under study. Conclusions: The scarce amount of data available on the evolution of treated alcoholism cannot be compared across studies due to considerable methodological differences. There is a need to promote common methodological criteria in relation to follow-up strategies. New statistical methods that permit longitudinal analysis for non-balanced and correlated data should also be incorporated.