In this review, we summarize the basic physiological and pharmacological properties of SLC26A9, outline its regulation and molecular interaction with CFTR, detail the role of SLC26A9 as a disease modifier in CF and potentially in other diseases, and finally discuss the impact of these discoveries on future research that is needed to explore this alternative chloride channel as a potential therapeutic target in the clinical arena. The gene discussed is SLC26A9; the disease is cystic fibrosis.