For decades, range of extension approaches has been employed in Ethiopia to support farmers with advice, technologies and new ways of doing things. Currently, agricultural extension service delivery approach his being implemented in link with ‘farmers group arranged in rural set up to facilitate extension delivery. It has been in place to more exercise participation of smallholder farmers in extension service delivery and to improve its coverage. The main objective of this systematic review was to examine the challenges of this model-farmer based extension approach in reaching smallholder farmers. The mode-farmer approach in the country has been given focus to compile it as best practices with the aim of being scaled up and out so that average productivity of the majority of follower smallholder farmers is to be transformed to the level of that of model farmers. However, because of very low mentoring capacity, this approach has poorly address the advisory needs of the follower farmers. Not compensating model farmers for their time and energy in supporting follower farmers, absence of clear guideline to identify and promote the use of model farmers in testing new innovations and sharing their knowledge and skills to other farmer, poor participatory planning that it is still dominated by village leaders or wealthier farmers and poor facilitation from extension system made still the voice of the poor farmers is neglected. Therefore, it needs further modifications in to address extension service demand of these needy smallholder farmers.