The invention relates to a materials supply contract system and method for use in conducting business on-line over a network of computers such as the Internet. A method is provided for a buyer to award a supply contract, issued as a BOM, to a supplier selected from a panel of predetermined suppliers which each have a base supply contract with the buyer, the method being conducted over a computer network which comprises at least one buyer computer, an administrator computer and at least two supplier computers, the method comprising the steps of sending a buyer message from the buyer computer to the administrator computer identifying the BOM which includes at least one predetermined parameter (e.g. material requirement, business and market rules and/or special instructions), receiving the buyer message and displaying the BOM on a site on the administrator computer which is accessible by at least two supplier computers, sending a BOM message from the administrator computer to the at least two suppliers, receiving and storing an offer message in the administrator computer from one or more of the at least two supplier computers which includes an offer to supply goods or services in accordance with the BOM, sending an acceptance message from the administrator computer to the supplier computer which sent the successful offer, and sending a notification message from the administrator computer to the buyer computer notifying the buyer computer of one or more of the offers.