In sensor networks, sensing coverage is an important issue. For target tracking and event monitoring applications, complete coverage is commonly used as one measure of coverage. However, when sensors are randomly distributed in the area of interest, complete coverage is too sensitive to the locations of the sensors. In this paper, point coverage is considered as an alternative measure of coverage. The probability of point coverage is derived. A comparison between complete coverage and point coverage is made by analysis and simulation as well. Such comparison can help network designers to make better decisions. (C) 2009 Elsevier Ltd. All rights reserved.