Therapeutic monoclonal antibodies, soluble cytokines and receptors to cytokines, and inhibitors of tyrosine kinase, are currently used in an ever increasing number of patients with neoplastic and inflammatory disorders. Their cutaneous side effects are not always well known by physicians in charge of these new biotherapies. However, these side effects seem to be relatively frequent and may seriously disturb the patients or even represent a life-threatening event. Accordingly, it appears necessary for dermatologists and physicians using these therapies to be aware of the varied patterns of skin complications they may cause, in order to manage the treatment in the safest and most comfortable way for the patients.