In an earlier work stable aberrations and dicentrics were determined by fluorescence in situ hybridization (FISH) after various doses of 137Cs gamma-rays. No corresponding calibration curve for dicentrics is available for determinations in terms of the conventional analysis as performed in our laboratory. In view of the potential for the application of chromosome painting to human biological dosimetry, it is desirable to determine such a calibration curve and this and the comparison of the resulting data to those obtained in terms of the FISH method is the objective of the present communication. In the study it is found that the linear-quadratic dose response curves for dicentrics, that are determined by the two methods, are significantly different, although the different target sizes are accounted for. A similar problem was found earlier for X-rays. It does not appear that the difference is due to technical difficulties in the FISH method, that has been improved by employing in addition to the whole chromosome DNA probes, a pan-centromeric DNA probe.