The paper analyses the impact of adopting new agricultural technologies on the multiple dimensions of food security for maize farmers in Tanzania. Relying on matching techniques, we use a nationally representative dataset collected over the period 2010/2011 to estimate the causal elects of using improved seeds and inorganic fertilizers on four dimensions: availability, access, utilization, and stability. We find an overall positive and significant impact on all the dimensions of food security even if substantial differences are observed. In particular, improved seeds show a stronger effect on food availability and access while inorganic fertilizers guarantee higher stability. In terms of utilization, both technologies increase the diet diversity while only improved seeds reduce the dependence on staple food. The study supports the idea that the relationship between new agricultural technologies and food security is a complex phenomenon which requires a deeper and more thorough investigation.