I believe they are a fruit botanically speaking, but a vegetable in terms of how they are generally eaten and prepared as they are not as sweet as most fruits. Apparently, they are not alone though. Wikipedia offers this: "Tomatoes are not the only food source with this ambiguity: green beans, eggplants, cucumbers, and squashes of all kinds (such as zucchini and pumpkins) are all botanically fruits, yet cooked as vegetables." Kind of makes me wonder why everyone always seems to get hung up tomatoes in particular as being fruits.