This study tests the validity of the hysteresis of unemployment rate for 37 developed and developing countries over the period 1993-2016 using the Sequential Panel Selection Method (SPSM) among nonlinear panel unit root tests and a nonlinear panel unit root test developed by Ucar and Omay (2009) with a Fourier function. According to the test results, 37 developed and developing countries are in a stationary process. The Panel KSS unit root tests with a Fourier function have shown long-term evidence in favour of 37 countries. According to the results of the analysis, it is concluded that the unemployment series are stable in all countries. This result is important in terms of the determination of long-term analysis in developed and developing countries.