Trademark is an important instrument for trade of trademark owner. The trademark protection was developed to prevent others to use the trademark of the trademark owner with the same category of products with those of the trademark owner, causing consumers' confusion on the source of products. Furthermore, the United States provide the protection on value existing inside the trademark so called "goodwill" in order to prevent others to misappropriate such intrinsic goodwill in the trademark and to prevent the dilution. Therefore, the trademark owner has also an exclusive right over the goodwill in the trademark; in particular of the sale promotion and the entry into new market, but the use of goodwill by the trademark owner may lead to monopoly and unfair competition. However, in Thailand, there is currently no protection on such goodwill. Thus it is excusive to study from the United States side on the conduct of the trademark owner in using the goodwill in the trademark, the impact as well as the solution model.