Dissertation (MSc Biodiversity Conservation)Sustainability of many rangelands including Simanjiro Maasai steppe rangelands is limited in part by invasive plant species. A study was conducted among two selected village rangelands (Terrat and Sukuro) of the Simanjiro district aimed to (1) determine the effect of Ipomoea hildebrandtii and I. kituiensis on herbage species composition, richness, and basal cover; and (2) determine the effect of Ipomoea hildebrandtii and I. kituiensis on herbage biomass productivity. Other objectives were to (3) assess the distribution of Ipomoea hildebrandtii and I. kituiensis across grassland and woodland habitats, and (4) evaluate the available mitigation measures among the Maasai pastoralists on the effects of Ipomoea hildebrandtii and I. kituiensis on their rangelands. A total of 10 plots of 70 m each with 9 quadrats of 1m22 each in the invaded and non-invaded grazing-lands coupled with point sampling technique. Purposeful sampling involved 10 key informants’ interviewees; 24 participants for focus group discussions. Simple random sampling involved 30 hamlets representatives for questionnaire surveys. Data on herbage species composition, richness, basal cover, biomass productivity; distribution of invasive Ipomoea spp; and mitigation measures for effects of invasive Ipomoea spp. Were analysed using STATA, Microsoft Excel and SPSS, respectively. Non-invaded grazing-lands had a higher basal cover (54.71%±1.95% for grasses, 45.29%±1.95% for forb) than invaded grazing-lands (29.38%±1.34% for grasses, 24.70%±1.20% for forb), (P<0.05). Herbage species composition between invaded and non-invaded grazing-lands doesn’t vary (P>0.05). Non-invaded grazing-lands had higher biomass productivity (0.289±0.03 t DM/ha) than invaded grazing-lands (0.202±0.02 t DM/ha), (P<0.05). Distribution of invasive Ipomoea spp. was higher in woodland (70%), wood grassland (80%), and grass woodland habitats (90%). Mechanical uprooting (100%) was noted as preferable mitigation measures for invasive Ipomoea spp. It could be concluded that the presence of Ipomoea hildebrandtii and I. kituiensis lowers herbage productivity. Thus, it is recommended that Maasai communities should establish a committee for rangelands management including mitigations of invasive plants. Keywords: Effect of invasive plants, Ipomoea spp., native herbage loss, Maasai steppe rangelands, and Simanjiro district..