Chronic rhinitis symptoms are among the most common problems presenting to physicians. When approaching this problem the diagnostic challenge is to determine the etiology, whether it is allergic, nonallergic, or perhaps an overlap of both conditions. Estimates of the prevalence of allergic rhinitis range from as low as 9% to as high as 42%. Although nonallergic rhinitis is a well-recognized diagnosis, its prevalence has not been studied definitively. If the assumption is made that approximately 20% of the U.S. population has allergic rhinitis, then 58 million people in the United States suffer from this diagnosis. Population survey results have estimated that 19 million Americans suffer from nonallergic rhinitis. Frequently, nonallergic rhinitis occurs in tandem with allergic disease and presents as mixed rhinitis. Because 44% of patients with allergic rhinitis may have concomitant nonallergic rhinitis, it is estimated that an additional 26 million people have a nonallergic component to their rhinitis (mixed rhinitis). Therefore, a total estimated 45 million people have either pure nonallergic rhinitis or mixed rhinitis. Because nonallergic rhinitis is common, it is important to differentiate this condition from rhinitis of allergic etiology. Once the diagnosis is established, an appropriate treatment plan tailored to a specific diagnosis can be optimally designed.