Theophylline was first isolated in 1888 and remains the most commonly used medication worldwide for the treatment of asthma. It decreases the need for asthma rescue medications by people who have asthma and is an effective steroid-sparing agent for patients who tolerate it. Recently, investigators have shown that theophylline decreases airway inflammation, accelerates eosinophil apoptosis, and decreases recruitment of lymphocytes and neutrophils to the lungs at low doses. It is classified as a phosphodiesterase (PDE) inhibitor, but its therapeutic mechanism of action remains undetermined. Theophylline should be reevaluated as a long-term medication for the treatment of asthma because of its ease of use, low cost, and recent evidence of its anti-inflammatory actions.