The empirical study examined the effect of farm size on scale efficiency of small holder tuber crop farmers in North central, Nigeria. Data used for the study were obtained from primary source using a multi-stage sampling technique with structured questionnaires administered to 300 randomly selected tuber crop farmers from the study area. Descriptive statistics such as means, standard deviations and percentages were used to summarize the variables used in the analysis while input–oriented data envelopment analysis (DEA) model was used to empirically determine the total technical, pure technical and scale efficiency with respect to farm size in the study area. The DEA results suggested that gains from improving technical efficiency exist in all farm categories, although they appear to be much higher on large and on medium farms than on small farms among tuber crop farmers in the study. The findings further revealed the mean pure technical efficiency of small, medium and large farms was 0.81, 0.69 and 0.59 respectively while mean scale efficiency of small, medium and large farms was 0.36, 0.40 and 0.50 respectively. The implication of these findings is that small farmers are fairly efficient in utilizing their resources and any expansion in the use of resources would bring more than proportionate increase in the output. The study therefore recommended that research efforts directed towards the generation of new technology, especially for small farmers, should be encouraged in the study area.