A training course named 'European Radiation Dosimetry Group/International Atomic Energy Agency Advanced Training Course on Internal Dose Assessment' was held in Czech Technical University in Prague from 2 to 6 February 2009. The course, jointly organised by the two organisations, had the aim of providing guidance on the application of IDEAS guidelines and of disseminating the results of EC CONRAD Project in relation to internal dosimetry (Work Package 5). At the end of the course a dose assessment exercise was proposed to participants. Four artificial cases, named exercises left to participants, were used to check the capabilities of application of the IDEAS guidelines, gained by participants during the event. The participants had to use both hand calculations and dedicated software, in limited time (7 h). Forty per cent of participants had solved all four cases in the allotted time. The results of the dose assessment were analysed to gain experience in types of errors assessors may make during the evaluations. The result of this intercomparison exercise was promising: half of the results in each case were equal to the 'reference evaluation estimate', which was obtained by applying the guidelines correctly.