20Background: Intestinal parasitoses still are a noticeable threat to public health. The 21 direct diagnosis of such parasites requires the use of concentration techniques, whose 22 sensitivities for protozoan cysts and helminth eggs are far from equal. 23 Aim: To compare the Willis, Ritchie and Bailenger concentration techniques in terms of 24 parasite recovery, cost, time, and biosafety.25 Methods: This prospective study analysed 236 stool specimens for intestinal parasites 26 using the direct wet smear and the above-mentioned concentration techniques applied 27 separately. 28 Results: Biphasic techniques identified significantly more positive specimens for 29 intestinal parasites than the Willis technique, the latter leading to less concentrated and 30 more altered parasitic elements on microscopy. No statistically significant difference 31 emerged from comparing Ritchie's and Bailenger's methods. The Willis technique was 32 the safest, yet the costliest and the most time-consuming of the studied methods.33 Conclusions: Even though the hazardous reagents employed may raise legitimate 34 concerns over their health implications, biphasic techniques prove to be uncostly, quick 35 to perform, and highly sensitive for detecting faecal parasites, therefore ensuring a safe 36 diagnosis for routine stool examinations. 37 38 39 40 227 This work forms part of the end of studies project of R. Guenichi and R. Hanchi, under 228 the supervision of S. Trabelsi, MD, Professor of Medicine. 229 This research received no specific grant from any funding agency in the public, 230 commercial, or not-for-profit sectors. The authors declare that they do not have any 231 commercial associations which might give rise to a conflict of interest in connection with 232