This research is focused on the applicability, in particular contexts, of roundabouts characterized by a non conventional geometry configuration. The methodology is based on the microsimulation approach, validated through a series of surveys on real case studies and traffic conditions. A microsimulation model (VISSIM, PTV), was applied in order to reproduce roundabouts geometry and to define vehicle flow parameters. The research results allow to evaluate roundabouts level of service as a function of geometric features and to establish the limits connected to the employment of noncircular roundabouts in different traffic scenarios.