Our aim is to describe the evolution of the telediagnostic service of the Telehealth Network of Minas Gerais (TNMG), a public telehealth service in Brazil. It started in 2006 with 82 cities, restricted to electrocardiography analysis. Currently it extends to 772 cities--performing also Holter, ambulatory blood pressure monitoring and retinography analysis--and 48 ambulances in the north of the state, as part of a myocardial infarction system of care. Using low-cost equipment and simple technology, TNMG has employed various strategies to increase telehealth use. The number of ECGs performed by TNMG has progressively increased. It was expected to achieve 2 million in February 2015. The utilization rates were around 90%. It proved to be economically sound, promoting savings of 45M USD for an investment of 10.2M USD. It is currently a regular health service in the state, integrated into the healthcare system. In conclusion, the telehealth model developed in Minas Gerais produced good clinical and economical results.