Two patients with a long-standing history of recalcitrant ankylosing spondylitis were commenced on adalimumab as monotherapy. Case 1 developed marked rapid deterioration in his previously stable vitiligo within 3 months of commencing treatment. This was attributed to anti-tumor necrosis factor (TNF) therapy, and a marked improvement was noted following withdrawal of adalimumab. Case 2 developed multiple new halo naevi over the trunk and limbs. They did not show dysplastic features and have remained unchanged despite continuation of treatment. Possible mechanisms and implications of the paradoxical occurrence of immune-mediated skin lesions seen in patients receiving anti-TNF therapies are discussed.