Rapid increase in the population of big cities creates the need for fast and cost-effective transportation systems. Bus Rapid Transit (BRT) in Istanbul has proved to be the most feasible system. This study provides information about the BRT in Istanbul and investigates the travel behaviours and attitudes of riders through data collected from 252 respondents to a questionnaire. The results demonstrate that the service quality of the BRT line has a significant effect on passenger attitudes. Respondents rated its capacity as insufficient, and 56% of the respondents valued the service more for its speed than for any other quality. Also, the socio-economic characteristics of riders have a significant effect on their use and their attitudes. Respondents in lower income levels use the BRT line more frequently than those in higher income levels. The results of the study canlead to improvements in the BRT line in future.