A comprehensive study of dispersion of surface Rayleigh wavesrnfor three paths: Gulf of Aden - Addis Ababa (GOA - AAE), Red SearnAddis Ababa (RES - AAE) and Arab republic of Egypt - Addis Ababarn(ARE - AAE), lying between north and east Africa is made. Earlierrnstudies of surface wave dispersion in the region were made for shortrnepicentral distances without considering contribution by differentrnmodes. The problem of contribution by different modes to dispersionrnis inherent at short epicentral distance ranges.rnRayleigh wave trains identified from seismograms of AddisrnAbaba seismic station (AAE) are enlarged and digitized. The resultsrnare analysed using fixed window Fourier analysis and moving windowrnanalysis (Landisman et a1. 1969). These methods have advantages inrndisplaying different modes which otherwise would be absent if thernusual peak and trough method is used.rnDispersion curves obtained by the above methods and the usualrnpeak and trough method are compared with theoretical dispersionrncurves generated for different crustal models. An efficientrnalgorithm developed for solving the period equation on a computerrn(Dunkin 1965; Robert H. Herrman personal communication 1980 ) isrnused to obtain theoretical dispersion curves up to ten modes.rnHowever, in this study the fundamental and first modes were foundrnadequate to explain the seismogram observations. A total of 150rntheoretical models each with multimode outputs were considered.rnA crustal thickness of 27 km with high Poisson's ratio overlyingrnan anomalous mantle (,d-- = 7.2 km/sec) 4 km thick is found forrnGOA - AAE path. For RES - AAE and ARE - AAE paths crustal thicknessesrnof 37 km and 38 km respectively overlying a normal mantlernare found. The Poisson's ratios for these paths are similar tornthat of a 'normal continental crust.rnRegarding resolution of modes for the period range consideredrnin this study both moving and fixed window methods give similarrnresults indicating that the former method is superfluous