The effect of dose rate on the induction of micronuclei (MN) in human peripheral blood lymphocytes was investigated over a range of dose rates from 0.125 Gy h^–1 to 178.2 Gy h^–1. The response of MN induction was fitted with a linear quadratic model and the α and β coefficients were estimated. It was found that β values decrease with decreasing dose rate as in the case of chromosomal aberration. At the dose rate of 0.125 Gy h^–1, pure linear response of MN induction was observed. An attempt was made to simulate the calibration curve for the purpose of biological dosimetry at different dose rates and exposure times. The yields when simulated with the exposure time or the dose rate are in agreement with experimental results.