Abstract: Irrational use of antibiotics is common in Bangladesh. The purpose of the present study was to know the effectiveness of various commonly used antimicrobials against Escherichia coli. Antimicrobial susceptibility test was done by Disc Diffusion method. In this study, antimicrobial resistance pattern of 163 isolates of Escherichia coli collected from various pathological specimens were determined. Most of the isolates (77%) were collected from urine sample. The highest numbers of isolates were resistant to cloxacillin (96.93%) and the lowest number isolates were resistant to imipenem (5.52%). Out of 163 isolates 141 (86.5%) were resistant to ampicillin, 89 (54.60%) to ceftazidime and 88 (53.99%) to ceftriaxone. From this study, it also appears that third generation cephalosporins (ceftazidime and ceftriaxone) were more effective against the test isolates in comparison to penicillin. The present study also revealed that 113 (69.33%) isolates were resistant to ciprofloxacin, 92 (56.44%) to chloramphenicol, 121 (74.23%) to co-trimoxazole and 128 (78.53%) to nalidixic acid. To the aminoglycoside drug 58 (35.58%) isolates were resistant to gentamicin and 74 (45.40%) to netilmicin. In this study 138 (84.66%) isolates were resistant to doxycycline, 126 (77.30%) isolates were resistant to tetracycline. Four isolates showed resistance to all the antimicrobials used except to imipenem. In the present study imipenem was found to be the most effective and 154 out of 163 isolates (94.48%) were found to be sensitive and cloxacillin was least effective and only 5 out of 163 isolates (3.07%) were sensitive to this penicillinase resistant drug.