In this paper, we examine the long-term effects of high school exit exams (HSEEs) on graduation rates and achievement using an interrupted time series approach. We find that introducing a HSEE has an overall positive effect on graduation rate trends, an effect which is heterogeneous over time. In the year of introduction and the following three years we find a negative impact of HSEE on graduation rates; this negative impact is short-lived and becomes positive over the long term. We perform robustness checks using states that do not have HSEEs as control group. We also estimate a pre-intervention negative effect, suggesting that high schools start preparing for the HSEE before its actual introduction. We find no effects for achievement, possibly due to the lack of meaningful cross-state achievement data in the time period studied.