The present study assessed the effects of occlusion duration and attention on components of the respiratory-related evoked potential (RREP). Twenty-nine channel evoked potential recordings were obtained from 12 young adults exposed to a pseudorandom sequence of 100-, 200-, 400-, and 800-ms inspiratory occlusions, under attend and ignore conditions. Results demonstrated that the duration of an inspiratory occlusion does not affect RREP components systematically, highlighting the importance of the onset of the occlusion in producing the cortical responses. Attention resulted in augmentation of the N1, P2, and P3 components but did not affect the early latency Nf and P1 components. P1, N1, and P3 occurred with shorter latencies in the attend condition. One subject with poor duration estimation ability displayed substantially delayed P3 latency. This result highlights the relationship between P3 and perception of respiratory somatosensory information.