In the daily clinic, patients with internet addiction show psychopathological patterns (tolerance, withdrawal, interpersonal conflict, mood modification, relapse) comparable to substance-related disorders. The outstanding psychological symptom which is reported by patients suffering from Internet addiction is the irresistibly urge to ‘be online’, which may cause psychobiological harm for the user and can lead to an addictive behavior. Also in the recent research literature it is assumed that Internet addiction as a subtype of behavioral addictions has commonalities in etiology, comorbidity and physiology with classical substance use disorders. Several representative epidemiological studies from different European countries revealed prevalence-rates of internet addiction in the general population ranging from 0.5 to 1 per cent. Taken into account that internet addiction is a common health problem, a special short term treatment program for Internet addiction, based on cognitive behavior-therapy (STICA) was developed. A pilot analysis of this manualized short -term treatment was performed in an open trial of the Grüsser-Sinopoli outpatient clinic for behavioral addiction. In this trial about 73 per cent of the treatment-seeking patients completed STICA regularly - whereas 27% of the patients terminated treatment prematurely and were considered as drop-outs. First outcomes concerning the change of concomitant assessed psychological measures will be presented.