Earlier evidence shows that motoneuron collaterals can form synaptic contacts with other motoneurons in spinal cord. We have recently shown that late-firing motoneurons (putative fast) receive 10-fold stronger recurrent excitation than their early-firing (putative slow) counterparts. This finding raises the question of whether connections between motoneurons are dominantly between fast motoneurons or whether slow motoneurons preferentially connect to fast ones. We performed paired recordings from motoneurons labelled from either gastrocnemius (ankle extensor) or tibialis anterior (ankle flexor) muscles. First, for synapses within the same motor nuclei, there was a large dominance of connections between fast motoneurons and only rarely we identified a slow motoneuron as the synaptic partner. We next tested whether it was possible to find connections between motoneurons belonging to antagonist nuclei. The synaptic connectivity across antagonist nuclei was similar to that observed within nuclei as synapses were observed dominantly between fast motoneurons. Surprisingly, recurrent excitatory synapses were not the only connection between antagonists. In one-third of the excitatory connections, recurrent inhibition was also observed between ankle flexors and extensors. Lastly, we have also detected recurrent excitatory connections between motoneurons which innervate proximal and distal leg muscles proving synaptic connectivity across joints. The function of these recurrent circuits is unclear but given the preferential fast-to-fast connectivity, it is possible that recurrent excitatory circuits are recruited during motor tasks that require the activation of many fast motor units, for instance during explosive movements. The antagonist inhibitory connectivity, on the other hand, could support reciprocal inhibition to facilitate locomotion.