During early brain development, γ-aminobutyric acid (GABA), the main inhibitory neurotransmitter in the adult brain, has been thought to be an important source of excitatory neurotransmission. This view, however, was recently challenged by a series of studies that claim that the excitatory effect of GABA is due to non-physiological in vitro experimental conditions. In this article, we aim to summarize results that support and challenge the traditional point of view, and indicate some strong and weak points of both positions.