Unreliability of financial statements in Iran has urged this country’s financial services industry management to manipulate practices by which they could gain reliable risk scores for borrowers. This research extracts the most influential qualitative factors that would impact the default of a business relationship borrower. Solicitation of the factors is done through Delphi methodology. The mean weight of each factor is then calculated from grades given to each factor by the experts. As a case study, lending relationships of a private bank, Karafarin Bank (KB), and hundreds of its relationship borrowers , are examined and the credit committee of the bank is asked to rate these companies according to the extracted attributes found by this research through Delphi method. The qualitative risk score of these companies are then derived and it is shown how this score could be used for estimation of a perceived default probability of customers