<b><i>Aim:</i></b> To clarify whether antithrombotic drugs affect diagnosis using the immunochemical faecal occult blood test ­(iFOBT) of colorectal neoplasia. <b><i>Methods:</i></b> Using the Japan Endoscopy Database from 8 centres between 2015 and 2017, we analyzed data about patients who were iFOBT positive and had received direct oral anticoagulants (DOAC), warfarin, aspirin or thienopyridine. One-to-one matching-analogue propensity score weighted analyses were performed to compare the positive predictive value (PPV) of all neoplasms, invasive and non-invasive colorectal cancers and adenomas between drug users and non-users. All neoplasms included invasive and non-invasive colorectal cancer, and adenomas. <b><i>Results:</i></b> We analyzed 197 DOAC users and 196 non-users, 153 warfarin users and 153 non-users, 408 aspirin users and 415 non-users, and 97 thienopyridine users and 97 non-users. No significant differences were observed in the PPV for all neoplasms (56.67 vs. 50.43%), invasive cancer (4.32 vs. 3.53%), non-invasive cancer (15.58 vs. 15.56%) or adenoma (53.13 vs. 48.09%) between the DOAC user and non-user groups. No significant differences were observed in the PPV for all neoplasia, invasive and non-invasive cancer, or adenoma between warfarin, aspirin and thienopyridine use and non-users. <b><i>Conclusions:</i></b> DOAC, warfarin, aspirin and thienopyridine use did not decrease the PPVs of the iFOBT used to evaluate all colorectal neoplasia.