During the currently evolving outbreak of monkeypox cases worldwide, 31 cases have been confirmed in the Netherlands up to 31 May 2022. Efforts to stop the spread of infection focus on active case finding, contact tracing of close contacts and their isolation or quarantine. Related recommendations from public health bodies on the need for active monitoring and isolation for a minimum of 21 days after the last day of exposure are based on the known monkeypox incubation period (up to 21 days).