Objective: to analyze adherence, non-adherence and abandonment of the monitoring of children referred to the high-risk reference centers of Rede Mãe Paranaense. Method: a parallel and convergent mixed-methods study, in which both approaches have the same weight. The study loci were two high-risk outpatient services from the South of the country. In the quantitative part, 3,107 medical charts of high-risk children were analyzed and the spatial distribution was performed. In the qualitative part, interviews were conducted with 29 health professionals, in addition to 34 family members, and content analysis was performed. Two databases were produced, which were analyzed separately and eventually integrated. Results: the rates regarding adherence to monitoring are decreasing, mainly in the municipalities that are far away from the high-risk outpatient services, and the non-adherence and abandonment rates are increasing. In the reports by the representatives and the manager, a failure was observed between the transportation offer and the active search flow of the absent patients, which contributes to the increase in the non-adherence and abandonment rates and to the consequent decrease in adherence. Conclusion: in high-risk children, adherence is decreasing and the non-adherence and abandonment rates increased.