Oprah Winfrey and Dr. Mehmet Oz are suing more than 50 businesses, saying they had used their names and images to sell beauty products and dietary supplements without permission.
Winfrey and the doctor, who is a frequent guest on her talk show, say the public is being deceived into thinking the two have endorsed products like acai berry, a fruit touted as a miracle weight loss supplement.
Their suit claims that following a show last year in which Oz discusses the Brazilian berry, internet ads started to appear featuring images of him and Winfrey.
Other products in dispute, the lawsuit alleges, include cosmetics, anti-wrinkle creams and tooth whitening products.
The lawsuit was filed in Manhattan Federal Court on Wednesday.