Psoriasis is a chronic inflammatory skin disease, which affects approximately 2.6% of the population in Northern Europe and Scandinavia. In order to achieve disease control, combinations of systemic treatments are sometimes needed for variable time periods. However, no evidence-based guidelines exist for the use of systemic combination therapy. Therefore, our aim was to review the current literature on systemic anti-psoriatic combination regimens. We searched PubMed and identified 98 papers describing 116 studies (23 randomized) reporting on the effect of various systemic combination treatments. The most thoroughly investigated combination was retinoid and phototherapy. Further controlled research is needed to define the safest and most effective combination regimens.