Efficiency measurement traditionally has been an important approach of evaluating public firm performance. The purpose of this paper is to estimate the technical efficiency of Trolley Buses of the Athens and Piraeus Area (TBAPA) in Greece for the year 2003. The estimation of technical efficiency is based on the Stochastic Frontier Analysis (SFA) and employs the Cobb-Douglas specification of the production function. Meanwhile, an attempt is made to investigate the explanatory power of other factors on the organization’s technical efficiency, such as the impact of other competitive means of transportation and the distance of the areas that each line connects. The panel data set consists of the monthly observations of the 20 lines of TBAPA for the year 2003. Finally, our findings are compared with those from Data Envelopment Analysis (DEA), a popular approach in the literature, providing, in general terms, consistent results.