A 59-year old man with moderate and stable psoriasis through 15 years was admitted to our Department with inadequately controlled type 2 diabetes. Treatment was initiated with the glucagon-like peptide-1 receptor (GLP-1R) agonist liraglutide. The patient experienced marked improvement in his psoriasis immediately after the start of liraglutide treatment. Itching stopped within days, scaling was reduced and spots of normal skin emerged. After 3 months, psoriasis was still improving. Excellent glycaemic control and a weight loss of approximately 8 kg over 3 months were moreover obtained. The patient had previously been well controlled in his diabetes without improvement in psoriasis, and the effect of liraglutide on psoriasis started before weight loss occurred. We discuss the possibility of a direct anti-inflammatory effect of liraglutide in psoriasis as well as indirect effects through improvement in comorbidities such as overweight. Randomized clinical trials are needed to reveal whether GLP-1R agonists represent a new therapeutic option for psoriasis.