Supply reliability is an important factor to be considered when planning and developing modern power distribution systems. If reliability value is expressed in monetary terms, it can be used as one input parameter when optimizing the electrical distribution systems and when developing regulation. This paper analyses the customer interruption cost (CIC) evaluation techniques and presents some results of CIC due to unexpected outages, obtained by different methods. The methods first discussed are customer surveys including direct worth estimation, willingness to pay and willingness to accept methods. As another group of methods, different indirect analytical methods are considered. The cases explored are residential, industrial, commercial and public customers in Finland
