This paper studies the causal effect of ultra-broadband (UBB) diffusion on healthcare utilization in Lombardy, Italy, between 2015 and 2019.

Exploiting variation in the gradual rollout of UBB infrastructure across municipalities, and measuring treatment intensity as the percentage of households covered by UBB, we estimate a difference-in-differences model for continuous treatments.

Using rich administrative data on outpatient diagnostic services and emergency room (ER) visits, we analyze how increased internet availability affects healthcare-seeking behavior.

Our results show that higher UBB coverage leads to a significant increase in outpatient diagnostic activity, with heterogeneous effects across diagnostic technologies and stronger responses among older individuals. At the same time, UBB expansion is associated with a reduction in ER utilization, particularly in inappropriate visits among younger individuals.

Overall, the results are consistent with a behavioral mechanism in which improved access to online health information increases diagnostic demand while reducing reliance on emergency care.

These findings highlight the role of digital infrastructure in shaping healthcare utilization patterns and have important implications for health policy in increasingly connected health systems.