This technical note studies distributed adaptive control of synchronization in complex networks. An effective distributed adaptive strategy to tune the coupling weights of a network is designed based on local information of node dynamics. The analysis is then extended to the case where only a small fraction of coupling weights can be adjusted. A general criterion is derived and it is found that synchronization can be reached if the subgraph consisting of the edges and nodes corresponding to the updated coupling weights is connected. Finally, simulation examples are given to illustrate the theoretical analysis.