Coexistence of ankylosing spondylitis with connective tissue diseases is very rare. Here, in this study, we describe a coexistence of ankylosing spondylitis and discoid lupus erythematosus in a 35-year-old man. He presented with a 5-year history of low back pain and concurrent development of a discoid rash. Inflammatory low back pain, HLA-B27 positivity and bilateral active sacroiliitis confirmed the diagnosis of ankylosing spondylitis. Discoid lupus erythematosus was diagnosed based on a skin biopsy. There are reports of discoid lupus associated with medications, particularly with tumour necrosis factor-alpha (TNF-α) blocking drugs. However, the patient presented here had coexistence of ankylosing spondylitis and discoid lupus before starting such treatments.