The Internet has increased at an exponential rate and for some people, can lead to problematic use. This review gives an overview of clinical services for problematic internet usage (PIU) including patient characteristics, available treatment, outcomes, and future clinical and research priorities. Psychological and physiological comorbidities are highly prevalent in individuals with PIU; the most widely and successfully used treatment is Cognitive Behavioural Therapy, although other psychological therapies such as reality therapy and family therapy, and pharmacological interventions, have also demonstrated preliminary success in reducing indicators of problematic use. PIU represents a clinically important syndrome, however it necessitates closer enquiry as the relationship with the different problematic behaviours that are facilitated by the internet needs to be more clearly understood.