The research was done to assess accessibility and adoption of improved maize and rice seeds among 200 smallholder farmers in Mbeya and Morogoro Regions. The specific objectives were to: assess smallholder farmers‟ knowledge on improved maize and rice seeds, assess smallholder farmers' attitude towards improved maize and rice seeds, determine the accessibility of improved maize and rice seeds, estimate the adoption rate of improved maize and rice seeds and determine the impacts of some socio-economic factors on the chances of smallholder farmers‟ adopting improved maize and rice seeds. Data were collected by mainly using a household questionnaire, and SPSS was used to analyse the data whereby, among other analyses, binary logistic regression was used to determine impacts of improved seed related factors on the chances of farmers adopting the seeds. The results showed that 66% and 81% of the household heads were aware of improved maize and rice seeds, respectively; and 29.0%, 7.5% and 63% of the respondents had unfavourable, neutral and favourable attitudes towards improved seeds. It was also found that the proportions of households which had access to improved maize and rice seeds were 40.5% and 34.5% respectively, while those which had adopted the seeds were 56.0% and 71.0%, respectively. The factors which had the highest positive impact on the chances of smallholder farmers adopting improved maize and seeds were land for rice production (Wald statistic = 51.772, p < 0.001) and farmers' awareness of improved seeds (Wald statistic = 8.515, p < 0.01). It is concluded that increasing acreage for rice and creation of more awareness about improved seeds are big determinants of adoption of improved seeds. Therefore, it is recommended that the government and other institutions dealing with agriculture should put more emphasis on accessibility and adoption of improved maize and rice seeds in order to improve rice and maize productivity in Tanzania.EPINAV Project