Classification of the herbacous vegetation of a heavily grazed rangeland in northern Kenya revealed four communities and a complex of extremely disturbed vegetation units. According to the ordination of relevés, two of these communities, the Chrysopogon-Hibiscusand the Sporobolus-Indigoferaassociation, represent a continuum that graded from stone covered and moderately grazed sites to smooth and heavily grazed pastures. From these, a Setaria acromelaena-Digera muricata association and an Achyranthes-Commelina association were distinctly separated. Whereas the former reflects moderately grazed pastures on clay soils, the latter occurs in shaded livestock resting places and in gallery woods. Finally, the relevés of the extremely disturbed vegetation originate from cattle tracks, watering places and livestock enclosures. Keywords: northern Kenya, semi-arid rangeland, herbivore pressure, increase of therophytes, decrease of perennial grasses, invasion of weedy species.