Purpose Fibres are regularly found within the delivery cartridge (DC) and in the anterior chamber (AC) during phacoemulsification cataract surgery (PCS) and postoperatively. The purpose of this study was to identify their frequency and possible significance. Setting Dedicated ophthalmic day surgery. Design Prospective, consecutive, singlesurgeon, cohort study. Methods In 639 eyes undergoing PCS, the presence of fibres was documented in or on both the DC and in the AC intraoperatively, and in the AC postoperatively. The intraoperative method of fibre removal was documented. Corrected distance visual acuity (CDVA) was recorded preoperatively, and at day 1, week 1, and week 4 postoperatively. The incidence of clinical cystoid macular oedema (CMO) and endophthalmitis in the retained fibre subcohort was compared with that of the non-fibre subcohort. Results A total of 5.2% of the operated eyes had a fibre or fibres in or on the DC, which in all cases was removed with forceps intraoperatively. A total of 14.6% of operated eyes had a fibre or fibres in the AC intraoperatively; these were removed by irrigation/aspiration. Postoperatively, five eyes (0.78%) had a fibre in the AC. There was no significant difference in postoperative CDVA between the fibre and non-fibre subcohorts (P ¼ 0.26), and no clinically significant CMO or endophthalmitis in either subcohort.