In common law jurisdictions, an implied warranty is a contract law term for certain assurances that are presumed to be made in the sale of products or real property, due to the circumstances of the sale. These assurances are characterized as warranties regardless of whether the seller has expressly promised them orally or in writing. They include an implied warranty of fitness for a particular purpose, an implied warranty of merchantability for products, implied warranty of workmanlike quality for services, and an implied warranty of habitability for a home.

The warranty of merchantability is implied, unless expressly disclaimed by name, or the sale is identified with the phrase "as is" or "with all faults". To be "merchantable", the goods must reasonably conform to an ordinary buyer's expectations, i.e., they are what they say they are. For example, a fruit that looks and smells good but has hidden defects would violate the implied warranty of merchantability if its quality does not meet the standards for such fruit "as passes ordinarily in the trade". In Massachusetts consumer protection law, it is illegal to disclaim this warranty on household goods sold to consumers.

The warranty of fitness for a particular purpose is implied when a buyer relies upon the seller to select the goods to fit a specific request. For example, this warranty is violated when a buyer asks a mechanic to provide snow tires and receives tires that are unsafe to use in snow. This implied warranty can also be expressly disclaimed by name, thereby shifting the risk of unfitness back to the buyer.

Another implied warranty is the warranty of title, which implies that the seller of goods has the right to sell them (e.g., they are not stolen, or patent infringements, or already sold to someone else). Theoretically, this saves a buyer from having to "pay twice" for a product, if it is confiscated by the rightful owner, but only if the seller can be found and makes restitution.