Aim: to evaluate the role of novel stocked irrigate that contains acids and antimicrobials as compared with the combined use of acids and antibiotics on contaminated root canals with E. faecalis and their role on eradication of biofilm. Methods: Seventy-eight freshly extracted single rooted permanent teeth were infected with an isolate of E. faecalis for biofilm formation. Teeth were divided into; Group 1: irrigated with 5-ml QMix™ contains an acid and antimicrobial (Q), Group 2: 5-ml 5% citric acid (C), Group 3: 5-ml 50-mg/ml of doxycycline (D1), Group 4: 5-ml 100-mg/ml of doxycycline (D2), Group 5: 5-ml mixture of doxycycline 50-mg as an antibiotic and 5% citric acid (D1A), Group 6: 5-ml mixture of doxycycline 100-mg as an antibiotic and a 5% citric acid (D2A). Successive paper points (n=3) placed to the WL for 1 minute then transferred to tubes containing 1-mL of 0.85% saline solution and agitated for 1-minute. Samples were diluted 10-fold in saline and aliquots of 0.1-ml were then plated onto Bile Esculin agar plates and incubated at 370 C for 48 hours. Visible colonies of E. faecalis were counted in every plate and the number of colonies/plate was multiplied by the corresponding dilution factor and by 10 to determine the total colony forming units (CFU) per ml of sample. Results: Group 1 showed the lowest mean count of CFU’s compared with the other 5 groups. Group 2 showed lower mean count of CFU’s than Groups D1, D2, D1A and D2A but higher than group Q. Group 3 and Group 4 respectively showed the highest mean count of CFU’s among other groups. Group 5 and Group 6 increasing the concentration of doxycycline did not affect significantly the mean bacterial counts while addition of Citric acid 5% to both groups decreased significantly the mean bacterial counts in groups D1A and D2A.