Good communication is an important constituent in the successful management of emergency situations in safety-critical systems such as large-scale chemical plants and nuclear power plants. To analyze the quality of communications among the main control room operators during the management of emergency situations, we developed the sentence completeness analysis method. The completeness of a sentence is defined by the completeness of each of the three important components of a sentence, which are the subject, the object, and the verb. An example analysis on the communications of two nuclear power plant operator teams in two simulated emergency situations shows a feasibility of the sentence completeness analysis. Discussions on the results of the example analysis are also included in the paper. (C) 2007 Published by Elsevier Ltd.