Trigeminal motoneurons relay the final output signals generated within the oral-motor pattern generating circuit(s) to muscles for execution of various motor patterns. In recent years, these motoneurons were shown to possess voltage dependent non-linear membrane properties that allow them to actively participate in sculpting their final output. A complete understanding of the factors controlling trigeminal motoneuronal (TMN) discharge during oral-motor activity requires, at a minimum, a detailed understanding of the palette of ion channels responsible for membrane excitability and a determination of whether these ion channels are targets for modulation. Towards that end, we have studied in detail the properties of calcium channels in TMNs and their susceptibility to modulation by 5-HT in rat brain slices. We found that based on pharmacological and voltage-dependent properties, high voltage-activated (HVA) N-type (-conotoxin GVIA (-CgTX) sensitive, and to a lesser extent P/Q-type (-agatoxin IVA (-Aga IVA) sensitive calcium channels make up the majority of the whole-cell calcium current. 5-HT (5.0 µM) decreased HVA current by 31.3 ± 2.2 % and the majority of this suppression resulted from reduction of current flow through N- and P/Q- type calcium channels. In contrast, 5-HT had no effect on low voltage activated currents (LVA) current amplitude in TMNs. HVA calcium current inhibition was mimicked by 5-CT, a 5-HT₁ receptor agonist, and by 8-OH-DPAT, a specific 5-HT_1A agonist. The effects of 5-HT were blocked by the 5-HT_1A antagonist NAN-190 but not by ketanserin, a 5 HT_2/1C antagonist. Under current clamp, -CgTX and 5-HT were most effective in suppressing the mAHP and both increased the spike frequency and input/output gain in response to current injection. Calcium current modulation by 5-HT_1A receptors likely is an important mechanism to fine tune the input/output gain of TMNs in response to small incoming synaptic inputs and accounts for some of the previously reported effects of 5-HT on TMN excitability during tonic and burst activity during oral-motor behavior.