Physiological noise correction of the BOLD signal requires information concerning the cardiac and respiratory activity. For EEG-fMRI, the burden of performing extra recordings may be alleviated by retrieving an ECG-derived respiratory signal (EDR). This work aimed to evaluate different methods for EDR estimation and subsequent derivation of fMRI respiratory regressors, by comparison with the measured respiratory signal, for EEG-fMRI. The feasibility of EDR estimation was demonstrated, with KPCA and PCA methods achieving the best performance. Nevertheless, similarities between EDRs and respiration were not directly reflected by the regressors, and the impact of using EDR-based respiratory regressors should be further examined.