Long waiting times are a common feature and a major concern in many public health care systems. They are often characterized as inefficient because they are a burden to patients without generating any gains for providers. There is an ongoing debate in Germany regarding the preferential treatment given to private health insurance (PHI) holders while statutory health insurance (SHI) holders face continuously increasing waiting times. In order to tackle this problem in the outpatient sector, Germany initiated a reform in 2015 which was aimed at providing SHI holders with appointments within an acceptable time frame. We exploit longitudinal experimental data to examine waiting times for six elective outpatient treatments in Germany for PHI and SHI holders before and after the reform. We find a considerable difference in waiting times favoring private patients. For SHI holders, waiting times remained stable over time (27.5 days in 2014, 30.7 days in 2016, Δ 3.2 days, p-value=0.889) while PHI holders experienced a significant improvement (13.5 days in 2014; 7.8 days in 2016; Δ 5.7 days, p-value=0.002). The results indicate that even after the reform there is still an unequal access to elective outpatient treatment depending on the patient’s insurance status.