Background: Premature chromosome condensation (PCC) is a method for interphase chromosome analysis in biodosimetry. This study was performed to verify the usefulness of PCC induced by calyculin A in human peripheral blood lymphocytes (pbl) for biological dosimetry and possible construction of dose-response curve.

Materials and Methods: Peripheral blood was obtained from a healthy donor and exposed to various doses (0.25–4 Gy) of γ -rays. The frequency of simple breaks and dicentrics were scored in G2/M chromosomes of Giemsa stained cells.

Results: Results show that the frequency of simple chromosome breaks appears to increase linearly with dose; while the frequency of dicentrics apparently increases linear-quadratically with the dose.

Conclusion: Induction of chromosome condensation by calyculin A is a powerful biodisimetric method, which provides a high number of spreads for analysis. With the use of this method, it is possible to overcome problems related to low mitotic index or cell-cycle alterations in routine metaphase analysis and low fusion rate in conventional PCC technique. Iran . J. Radiat. Res., 2004; 2 (1): 15-20