Purpose: The compare the suitability of PAINT and conventional nomenclature systems for the construction of chromosome aberration dose- effect curves for X-rays using FISH techniques, and to compare these curves with those based on solid-stained dicentrics analysed in first division metaphases by the FPG technique. Materials and methods: Blood samples were irradiated at 0.1, 0.25, 0.50, 0.75, 1, 1.5, 2, 3, 4 and 5 Gy 180 kV X-rays. FISH painting was performed using probes for chromosomes 1, 4 and 11 in combination with a pan-centromeric probe. Results: Translocations showed a higher background frequency than dicentrics. This influences the ratio of translocations:dicentrics at the lower doses and the uncertainties of dose- effect curves for translocations. The dose-effect curves for dicentrics obtained by FISH and solid stain were in close agreement. Conclusion: For short-term biological dosimetry purposes by FISH, the use of dic(BA) (PAINT nomenclature) or total dicentrics (conventional nomenclature) should give similar dose estimates. For dose reconstruction, the use of total or complete translocations result in similar uncertainties.