One of the first known effects of space weather on GPS was fluctuations in the amplitudes and phase of GPS radio signals known as ionospheric scintillation. This thesis aims at studying the behavior of ionospheric scintillations during selected geomagnetic storm days of 2012 - 2015 at Bahir Dar station to investigate the effects of geomagnetic storm on ionospheric scintillation using data extracted from dual frequency GPS-SCINDA receiver installed at Bahir Dar (Ethiopia) and Omniweb data explorer. For this study the scintillation data are examined by taking a TEC data of five disturbed days of March 2012, June 2013 and March 2015 by adding two days data from back and forth of geomagnetic storm days are analyzed by using MATLAB code. We have compared our results with the criteria proposed by Aaron. The results of the given data indicates that the effect of storm on vertical total electron content (vTEC) is enhancement and that of ionospheric scintillation is suppression which contradict Aaron’s criteria. The current observations from this study are significant to satellite communication, particularly those planning communication links at low latitude regions