MiDA, in March 2008, instituted a four year project in the Afram Basin with the aim of enhancing the productivity of the farmers (including maize farmers) in the basin. Although the project ended in February 2012, the question of the effect of the project on the productivity of maize farmers in the zone from the point of view of an independent body remains unknown. Therefore this study assessed the effect of MiDA intervention on the productivity of maize farmers in the Afram basin of Ghana. Farmers’ perceptions of MiDA intervention were assess using a three point likert-type scale and analyzed using percentages. A partial factor productivity index, yield, was used to estimate the level of productivity of both participant and non-participant maize farmers. The PSM method was adopted to assess the effect of MiDA intervention on the productivity of the participant maize farmers. Purposive sampling was used to select four out of nine districts in the basin in which the intervention was carried out based on the intensity of maize production in the districts. Again, purposive sampling was used to select two communities in each district from which simple random sampling was used to select 25 participant and 50 non-participant maize farmers from each district to give a total of 300 maize farmers. Results from the data collected indicates that majority of both participant and non-participant maize farmers (81.3%) were of the view that the intervention has helped increase the yields of participant farmers with most of them (88.3%) recommending the repetition of the intervention. The main limitation of the MiDA intervention, according to the farmers, was the late purchase of the maize grain by MiDA. The main proposal the farmers suggested should be included in the intervention, if it was to be implemented again, was to provide them with some facilities and equipment. The mean yield of the participant farmers was 1.51 Mt/ha with that of the non-participant farmers being 0.86 Mt/ha. Also, the study revealed that maize yields of farmers vary across districts but are the same across regions. There was no significant difference between the mean yields of participant males and participant females although the mean yield of non-participant males was higher than the mean yield of non-participant females. Lastly, the study revealed that participation in MiDA intervention has a positive and significant effect on the productivity of the participants with participation in the intervention increasing the yields of the participants by 0.6680 Mt/ha. The results suggest that MiDA intervention was successful from the point of view of the farmers although there were a few limitations. In addition, it can be concluded that participation in MiDA intervention enhanced the productivity of the participant maize farmers. This study thus recommends that organizations that aim at enhancing the productivity of maize farmers such as MiDA and MoFA should undertake more of such interventions.