This paper analyses the level of using the software functional size measurement methods by the Polish providers of dedicated business software systemsas well as the reasons behind this
. The surveys were conducted against a background of author’s own research concerning the usage of software development and enhancement projects effort estimation methods. The use of both types of methods was examined in two cycles: at the turn of the year 2005/2006, being the time of economic prosperity, and next at the turn of the year 2008/2009, that is in the initial stage of crisis and increased investment uncertainty associated with it. This paper presents the most significant conclusions coming from the results of both surveys as well as from comparative analysis of the two.