Background/objective In this radioanatomical study with clinical correlate, we study a variation of the ‘extended nasal floor mucosa’ (ENFM) free-graft, the purely nasal floor mucosa (PuNFM) free-graft. The objectives of this study are to evaluate the coverage surface area provided by the PuNFM, study the adequacy of the PuNFM in the reconstruction of endoscopic endonasal approach (EEA) transsellar postoperative defects and compare and evaluate this reconstructive technique with current sellar region reconstruction practices. Methods Dissections were performed on five cadaveric specimens. PuNFM were harvested bilaterally and the area provided for reconstruction was calculated. Twenty-five consecutive cases of pituitary adenomas resected through an EEA were analyzed to estimate the sellar defect surface area (SDSA) after a transsellar EEA and calculate the area of PuNFM bilaterally. Results The median cadaveric SDSA was 4.77 cm2, with a median left and right side PuNFM area of 5.09 and 5.19 cm2, respectively. Clinically, the median SDSA was 5.36 cm2, and the total radiological PuNFM surface area was 5.46 cm2, with modified Knosp grade >2 tumors having larger SDSA than that of Knosp grade <2 tumors. The PuNFM graft proved to be most effective for covering modified Knosp <2 tumor defects. Conclusions The PuNFM represents a variation of the ENFM free-graft sellar defect reconstruction technique that provides sufficient surface area to reconstruct the majority of the sellar defects related to transsellar EAA for pituitary adenomas. This technique may positively impact sinonasal function and quality of life. Future prospective clinical studies are needed to verify these findings.