This paper develops a new derivative estimator using variable structure system (VSS) and adaptive techniques. The proposed nonlinear adaptive variable structure derivative estimator requires little knowledge about the observed signal source and is able to handle the observed signals that are the outputs of either linear or nonlinear dynamic systems with uncertainties. In the absence of system noise, the uniform boundedness of the proposed derivative estimation is guaranteed by means of the adaptive control approach. By virtue of VSS, the new derivative estimator is capable of adapting itself to the noise environment, especially the unpredictable changes in system noise.