Abstract Background The National Immunization Program Information System (SIPNI - Sistema de Informação do Programa Nacional de Imunização) in Brazil is a technological innovation management tool that enhances the performance of managers and health professionals in the evaluation and monitoring of immunization activities. In the country, the decentralization of the System is at an advanced stage, but it still faces challenges regarding its operation and use, impacting on its results. This study aims to evaluate the deployment of SIPNI in the state of Minas Gerais, in 2017. Method Cross-section study performed in Primary Healthcare vaccination rooms in 54 municipalities in the Brazilian state of Minas Gerais, in 2017. A multidimensional questionnaire was used with nursing professionals who work in vaccination rooms, containing questions about the structure (presence of an internet-connected computer, instruction manual, software version, IT professional for technical support, trained healthcare professional, use of communication channels to obtain system information) and the process (activities performed by the staff to operate the immunization information system) of their work. Those questions refer to the components of the information system: system management, immunized-patient records, and Movement of Immunobiological. Implementation Degree (ID) was defined by a score system with different weights for each criterion, according to the importance level observed in it, with a rating of: adequate, partially adequate, inadequate and critically inadequate. For data analysis, median was used as the summary measure, and Pearson’s Chi-Squared Test was used for proportion comparison. Results Municipal SIPNI is not adequately implemented and that results mainly from the actions performed in health service units, indicating problems in the use of technology by professionals working in vaccination rooms. The structure was better evaluated than the process, presenting IDs of 70.9 and 59.5%, respectively. Insufficient internet access, inadequate use of communication channels, and lack of professional qualification were some of the identified structural issues. “Movement of Immunobiological” was the best-ranked component (ID = 68.5%), followed by “immunized patient records” (ID = 59.3%) and “SIPNI management” (ID = 50.7%). Partial performance of SIPNI is independent of population size in the municipality and of FSH coverage. Conclusions SIPNI is still an underutilized technological innovation. There are challenges that must be overcome, such as implementation of the final web version, internet connectivity, and capabilities aimed at the use of information generated by technology. Nevertheless, perspectives regarding SIPNI are positive, with functionalities to optimize activities in vaccination rooms.