In Tanzania, agriculture remains the largest sector of the economy, and hence its performance has substantial impacts on income and poverty. Round potatoes are grown in all continents under various climatic conditions. Smallholder farmers in Mbeya Rural and Makete Districts in Tanzania recognise the potential of round potatoes as a crop contributing significantly to household income and food security. The purpose of this study was to determine the contribution of potato production to household income in Mbeya and Makete Districts in the southern highlands of Tanzania. The specific objectives of the research were to: (1) analyse round potato production and other crops grown in the study area, (2) assess household income from round potato and from other sources in the study area and (3) determine the impact of round potato production on household income. A cross-sectional research involving 233 potato farmers was conducted in March 2012 through structured interviews using a questionnaire, focus group discussions and key informant interviews. The dependent variable, household income, was regressed on eight independent variables to find the impact of each of them on the dependent variable. The results showed that there was high positive significant impact of income from round potato per adjusted adult equivalent unit (AAEU) on household income (p < 0.001). It is concluded that round potatoes are more profitable than other major crops grown in the study area. Moreover, if given due attention and care, round potatoes can contribute greatly to household income. It is recommended that the government should support farmers in terms of availability of inputs, training on improved agricultural technologies and support for research on round potatoes so that they can help increase household income.Commission for Science and Technology Tanzania (COSTECH)