In 2016 Chile adopted a new law (Ley N° 20.915) that aims to strengthen the public and democratic character of the political parties and facilitate their modernization. For the political parties in the country this means a set of measures imposing obligations concerning their transparent and democratizing internal processes. The aim of this paper is to examine how the transparency within the Chilean political parties has changed since the introduction of the law 20.915 and how the citizens trust for these political entities has changed during the same period. What have the political parties done to increase the transparency? How has the relationship between transparency and trust in the political parties developed since the introduction of the law 20.915? What factors are important for understanding the relationship between transparency and trust? Is the increased trust in political parties due to the introduction of the law 20.915 or are there other aspects to consider? The theoretical framework resulted in two hypotheses. The first is based on the idea that increased transparency in political parties leads to higher trust for the political parties and therefore expect trust in parties in Chile to increase. The second hypothesis take into account that this effect might be stronger in the short run, but over time the effect will diminsh because there are other aspects to take into consideration as well, and if these are not seen to, the trust won’t continue to increase alongside the transparency. The expectations of the first hypothesis received support as both transparency and trust increased after the introduction of transparency reforms. But the indication of such relationship diverged at the end of the period, when trust decreased despite the continued improvement of transparency. This could be seen as an indication of support for the expected outcome of the second hypothesis, and the discussion concerning the reason for this result focused on the role of perception of corruption, time, medial attention and social media platforms among others. The analysis has been conducted through a qualitative case study based on various documents and scientific articles. The method used is both descriptive and theory trying since the paper aims to answer both questions as “how”, “what” and “which”, and also aims to test the stated hypotheses on the empirical material.