The use of mobile phones while riding is one of the major causes of road accidents. Despite of its danger, the use of mobile phones while riding is still widely found in Indonesia, especially among taxi riders because it is perceived as an important and beneficial activity since they rely much on the mobile application to do their job. The purpose of this study is to assess the behaviour of taxi riders when using a mobile phone while riding. The research was conducted by observing 125 taxi riders in Bandung, one major city in Indonesia. The results show that the most activities carried out on mobile phone while riding were the use of GPS (44.8%), sending messages (1.6%), and making phone calls (1.6%). Importantly, taxi riders’ response to a telephone call are: 69.6% chose to ignore the call, 24.8% chose to pick up the telephone while riding, and 5.6% chose to pull over before picking up the call.