Improved maize seed is instrumental to deliver an Asian-style ‘green revolution’ for Africa. The paper reviews and makes a comparative analysis of the maize (corn) seed sector and its evolution in Kenya, Tanzania, Uganda and Ethiopia drawing from seed sector surveys and secondary data. Enhancing farmers’ access to and use of new maize varieties still presents a number of challenges in eastern Africa – not least due to a number of policy and institutional impediments to the development of the seed sector. The regional seed sectors also show some remarkable contrasts: they have evolved at different speeds and in different directions, driven by diverging agricultural growth opportunities and varying degrees of regulation, liberalization and restructuring. The paper reiterates calls for an enabling environment for private seed companies to evolve in order to serve the diverse farmer communities so that they benefit from existing and future improved maize seed opportunities.