The kinetics of chain exchange between diblock copolymer micelles in solution at equilibrium were studied by dissipative particle dynamics simulation. We performed hybridization simulations for A₂B₃ or A₄B_x (x = 4, 6, 8) micelle solutions in which approximately half of all micelles and free chains were initially colored and chain exchange between micelles was monitored by analyzing the time-dependent fraction of colored chains in aggregates. We found that in all cases the chain exchange is dominated by chain (or small aggregate) expulsion and follows a first-order kinetic process with the characteristic time, τ, increasing exponentially with core block length, N_A and interaction parameter between blocks, χ_AB as τ ≈ exp (0.67χ_ABN_A). We determined that chain exchange between micelles does not depend on concentration but occurs via several kinetic mechanisms: unimer expulsion/insertion, small aggregate fragmentation/merging and unequal size micelle fission/fusion, which all exhibit very similar relaxation times. Chain exchange between micelles in A₄B_x micelle solutions is found to occur more rapidly for diblock copolymers with a longer corona-block length, as the area per chain and critical micelle concentration are larger (while micelle size and critical micelle temperature are lower) in this case, implying a lower potential barrier for chain (or small aggregate) expulsion from micelles.