Inhibitory synaptic inputs to Renshaw cells are concentrated on the soma and the juxtasomatic dendrites. In the present study, we investigated whether this proximal bias leads to more effective inhibition under different neuronal operating conditions. Using compartmental models based on detailed anatomical measurements of intracellularly stained Renshaw cells, we compared the inhibition produced by glycine/GABA synapses when distributed with a proximal bias to the inhibition produced when the same synapses were distributed uniformly (i.e. with no regional bias). The comparison was conducted in subthreshold and suprathreshold conditions. The latter were mimicked by voltage-clamping the soma to -55 mV. The voltage-clamp reduces non-linear interactions between excitatory and inhibitory synapses. We hypothesized that for electrotonically compact cells like Renshaw cells, the strength of the inhibition would become much less dependent of synaptic location in suprathreshold conditions. This hypothesis was not confirmed. The inhibition produced when inhibitory inputs were proximally distributed was always stronger than when the same inputs were uniformly distributed. In fact, the relative effectiveness of proximally distributed inhibitory inputs over uniformly distributed synapses was greater in suprathreshold conditions than in subthreshold conditions. The somatic voltage-clamp minimized saturation of inhibitory driving potentials. Since this effect was greatest near the soma, the current produced by more distal synapses suffered a greater loss due to saturation. Conversely, in subthreshold conditions, the effectiveness of proximal synapses was greatly reduced at high levels of background synaptic activity due to saturation. Our results suggest glycine/GABA synapses on Renshaw cells are strategically distributed to block the powerful excitatory drive produced by recurrent collaterals from motoneurons.