Cyanobacteria recruitment from sediments is an important seed bank for their pelagic abundance. We esli-mated cyanobacteria recruitment from sediments with migration traps in Lake Taihu from March to June2005, measured in situ growth rate of cyanobacteria in the water column in specially designed chambers, and compared the sizes of both processes. Meanwhile the effect of zooplankton grazing on cyanobacteria growth rate was also measured. Cyanobacteria recruitment increased wilh some degree of fluctuation from March to June, peaking in April; in situ grow ill rate of cyanobacteria also showed a general increase at the same time, only reached maximum in early May. No obvious effect of zoop tank ton grazing was observed on the in situ cyanobacteria growth rate. Cyanobacteria recruitment only art'ounled for a small portion of the pelagic growth (<2.5%) thereby suggesting that future research on cyanohaoteria hlooni (ievelop-ment be focused on the pelagic populations in water column.