9pSmallholder farmers in Mbeya Rural and Makete Districts recognise food insecurity as a problem affecting them. They also recognise the potential of round potato as a crop contributing to household food security. However, the extent to which the crop contributes to food security had not been quantified. The purpose of this study was to determine the contribution of potato production to household food security in Mbeya and Makete Districts in the Southern Highlands of Tanzania. The specific objectives of the paper are to: (1) analyse round potato production and other crops grown in the study area, (2) assess food security in terms of dietary energy consumed (DEC) and (3) determine the impact of round potato production on food security. Multistage sampling was used to select 233 potato farmers. The research was a cross-sectional one and was conducted mainly through structured interviews using a questionnaire, which was supplemented with focus group discussions and key informant interviews. The dependent variable, food security in terms of dietary energy consumed per adult equivalent per day, was regressed on seven independent variables to find the impact of each of them on the dependent variable. The variables were household size, age of household head, DEC from potato, income from potato, income from other crops, years of schooling of household head and income from non-agricultural activities. The results showed that there were positive significant impacts of DEC from potato, household size and income from nonagricultural activities on food security. It is recommended that the government should support farmers in terms of availability of inputs, training on improved technologies and support research on round potato.