With reference to the prototype of neutron inspection portal built and successfully tested in the Rijeka seaport (Croatia) within the EURITRACK (EURopean Illicit Trafficking Countermeasures Kit) project, an assessment of the biological shielding in different set-up configurations of a future portal has been calculated with MCNP Monte Carlo code in the frame of the Eritr@C (European Riposte against Illicit TR@ffiCking) project. In the configurations analyzed the compliance with the dose limits for workers and the population stated by the European legislation is provided by appropriate shielding of the neutron sources and by the delimitation of a controlled area. ► We assess the biological shielding of a inspection portal based on neutron sources. ► Different configurations of the system have been calculated with MCNP code. ► The work has been performed within the European Eritr@C project. ► The compliance with the European dose limits has been verified for each configuration. ► It is provided by shielding of the neutron sources and by delimitation of a controlled area.