An express warranty is any affirmation of fact or a promise made by a seller to a buyer which relates to the subject matter of the agreement and becomes a part of the basis of the bargain. It is not necessary to the creation of an express warranty that the seller use formal words such as warrant or guarantee or that the seller have a specific intention to make a warranty.

The elements of a claim for breach of express warranty for services are (1) the defendant sold services to the plaintiff; (2) the defendant made a representation to the plaintiff about the characteristics or quality of the services by affirmation of fact, by promise, or by description; (3) the representation became part of the basis of the bargain; (4) the defendant breached the warranty; (5) the plaintiff notified the defendant of the breach; and (6) the plaintiff suffered injury.

Privity (a direct relationship between the parties) is not required where the defendant furnishes samples to a middleman or makes a transferable express warranty knowing the samples or warranty will likely be submitted to the ultimate buyer.

In Missouri, an express warranty is created when a seller makes a specific affirmation of fact, promise, or description about the services being sold, and this representation forms part of the basis of the agreement between the seller and buyer. The creation of an express warranty does not require the use of formal words such as 'warrant' or 'guarantee,' nor does it require the seller to have an explicit intention to make a warranty. To claim a breach of express warranty for services in Missouri, a plaintiff must demonstrate that the seller sold services to them, made a representation about the services that became part of the contract, breached this warranty, and that the plaintiff notified the seller of the breach and suffered an injury as a result. Importantly, Missouri law does not require privity of contract for a breach of express warranty claim when the seller provides samples to a middleman or makes a transferable warranty, with the understanding that it will likely reach the ultimate buyer.