Since the 1980s, almost all of the Hungarian narrow-gauge railway lines underwent a complete change of function. About 120-140 years ago, narrow-gauge railways were created mainly for economic purposes. Nowadays, with a few exceptions, freight operation is completely eliminated and replaced by tourism. In my study, I deal with two questions: on the one hand, I will examine the place of the existing narrow-gauge railways in the tourism system. In this context, I will present the tourism potential of narrow-gauge railways. These include, for example, the availability of narrow-gauge railways, their inclusion in the wider tourism system, the material conditions of the basic infrastructure of narrow-gauge railways, etc. On the other hand, by presenting four railway lines from South Transdanubia, I will examine how well the opportunities offered by tourism have been exploited at the local level, what the impact of narrow-gauge railways is on tourism, and what the tourism-related significance of these lines is at all. Based on my analysis, it can be concluded that the narrow-gauge railway sector is developing within the tourism system, and compared to the period before the COVID-19 pandemic (2020–2021), investments, technical developments, and attendance have also increased. It is also clear from the South Transdanubian cases that the narrow-gauge railway system is becoming more and more important especially where it can be connected to other tourist attractions (natural parks, forest schools, etc. ), which is also evident in the attendance indicators.