A cursory survey on the nature and structure of the informal financial sector (IFS) in the SEACEN countries is provided in this paper. Section I gives an idea on the size and magnitude of IFS in the SEACEN countries. The types of credit supplied by the IFS are also examined. Section II is an analysis of the utilization of credit by the borrowers in the IFS, while Section III examines the trend and structure of interest rates in the IFS. The concluding section attempts to rationalize the persistence of IFS despite various efforts on the part of the SEACEN government to contain their activities.