A computerized expert system reviews and adjudicates medical health car e payment requests made by physicians to payers, such as insurers, for procedures performed and services and materials rendered to patients in the course of treatment. The system adjudicates a payment request to minimize fraud and mistakes and to determine whether to honor the request and if the request is honored, the dollar amount of the payment. The expert system reviews the payment request based on user-specified review criteria. Such criteria reflects contractual arrangements between payers, providers and patients, current, locally acceptable medical practices and patient and provider payment request patterns. To perform the review, the expert system obtains relevant prior payment requests as necessary according to the user' s pre-determined review criteria ; defines a master list of payable payment requests given current medical procedures, the pre- determined parameters of the review and specific contractual arrangements between the payer, patient and health care provider; analyses the current payment request according to the relevant historical payment requests and the master payable list by applying user-defined interpretive rules to this information; and develops a nd reports payment decisions based on that analysis.