The biological half-time of cadmium in the blood of previously exposed workers was estimated after the cessation of exposure. Five men were followed for a period of 10 to 13 years. One-compartment and two-compartment exponential elimination models were used to describe the decrease in blood cadmium levels over time. The best fit to the observed data was obtained with a two-compartment model. The half-times estimated from this model ranged from 75 to 128 d for the fast component and from 7.4 to 16.0 years for the slow component. The results confirm that there is a very long whole-body biological half-time for cadmium, and the estimated half-times are similar to those obtained with different methods.