##submission.abstract##
Lithium is the mainstay of treatment in bipolar disorder and is associated with a variety of cutaneous side effects including psoriasis, acne form eruptions and folliculitis. Lithium can induce denovo psoriasis or exacerbate pre-existing psoriasis, the later one being most common. We report a case of lithium induced denovo scalp psoriasis and psoriatic arthritis in a patient who was on lithium since 17yr for bipolar affective disorder. Though scalp psoriasis is one of the commonly induced type, psoriatic arthritis due to lithium is very rare and only one case report was published so far.Also, as lithium is one of the commonly prescribed drug in psychiatry, the cutaneous side effects are to be known for psychiatrists and dermatologists.