South African Journal of Agricultural Extension, Vol. 49 No. 1, pp. 59-80The objective of the study was to establish the actors’ roles and functions in improved rice varieties innovation system in the Eastern Zone of Tanzania. The target population samples for the study comprised of household heads (n = 340) and other key identified actors (n = 99). The research design was a convergent parallel mixed method. Face-to-face interviews, focus group discussions and documentary review were used to collect the data. The findings indicate weak or inability of Agricultural Seed Agency, TANSEED International Ltd, Quality Declared Seed producers in seed multiplication and distribution and agro-dealers were not selling quality rice seeds, thereby resulting in low availability and high prices of the same. Also, the findings show weak participation of farmers, agro- dealers, traders and millers in the functions of guidance of the search and rice varieties development, and the limited number of market actors and weak credit mobilization for farmers to invest in IRVs. The study recommends for the Government of Tanzania to create enabling environment that enhances participation of all key actors in the processes of guidance of the search and rice varieties development; linking farmers with external markets; and enhancing the farmers’ access to credit facilities by working on the obstacles hampering farmers from accessing loans from financial institutions.