Administrative and economic corruption in Iran has acquired a structural and multi-layered nature, the roots of which extend beyond mere weaknesses in laws and formal institutions. This study, using a qualitative approach and thematic analysis, examines the role of informal barriers—particularly "culture of corruption" and "networks of influence"—in the failure of anti-corruption policies. Data were collected through 18 semi-structured interviews with experts and analysis of official documents. The findings reveal that the "culture of corruption," by normalizing violations, weakening legal norms, and prioritizing personal relations over formal regulations, provides fertile ground for the reproduction of corruption. Meanwhile, "networks of influence," by leveraging political and economic ties, circumvent formal oversight and create institutional immunity for their members. The interaction between these two factors forms a self-reinforcing cycle of corruption, in which public culture legitimizes corrupt behavior and power networks consolidate it. Relying on the framework of New Institutionalism and focusing on the distinction between formal and informal institutions, this research seeks to answer the question: How does the interaction between the culture of corruption and networks of influence lead to the reproduction of institutional corruption in Iran? The results indicate that effectively combating corruption requires moving beyond purely legal approaches and simultaneously addressing institutional, cultural, and structural reforms.