GillespieGUI is a new user interface for biochemical networks that has been designed to integrate both tasks of interest to biologists - namely, simulating a model and analyzing the data. The data simulation is carried out by a stochastic simulator, whose parameters such as simulation start and end times, as well as data or time sampling options can be set prior to starting the simulation. This being a tool designed for statistical analysis, users can specify the number of runs of the model that the simulation should generate. Once the data for the specified number of runs has been generated, the tool then computes correlations between various species, along with their power spectral densities and transfer functions. In particular the following capabilities are supported: