This is a double blind (a medical research study in which neither the researchers nor the participants know what treatment the participants is receiving), randomized (study drug is assigned by chance), placebo-controlled, parallel group (a medical research study comparing the response in 2 or more groups of participants receiving different interventions [treatments]) and up-titration study in participants with chronic low back pain. The study will consist of 6 visits (Day -7 to Day -1 [Visit 1], Day 1 [Visit 2], Day 3 [telephone visit], Day 8 [Visit 3], Day 15 [Visit 4] and Day 29 [Visit 5]) and 2 phases: a screening phase and treatment phase. Screening phase will be of 7 days during which, participants will receive stable dose of non-steroidal anti-inflammatory drugs (NSAIDS) or COX-2 selective inhibitors (NSAID that specifically inhibits an enzyme known as cyclooxygenase-2) for pain therapy. On the basis of average pain intensity over the last 48 hours which will be measured at baseline (at the end of screening period), participants will enter the treatment phase. Treatment phase will be of 28 days which includes 7-days of dose titration period. In treatment phase all participants will be randomly assigned to 1 of 2 possible treatments: tramadol HCl 75 milligram (mg)/acetaminophen 650 mg ER tablet treatment or the equivalent placebo (an inactive substance) treatment until study completion, Day 29. Participants will receive 1 tablet of tramadol HCl/acetaminophen ER or its equivalent placebo, once daily for 3 days. After the first 3 days, the participants will receive a telephone inquiry monitoring the occurrence of adverse events and will be given additional administration instructions for the next 4 days (1 tablet twice daily for 4 days). From Day 7, participants will receive 1 or 2 tablets twice a day depending on the degree of pain relief required. Participants will visit the center on the Day 8 (Visit 3), Day 15 (Visit 4), and Day 29 (Visit 5) after starting study drug. The efficacy will be assessed by measuring extent of reduction in pain intensity on a Visual Analog Scale (VAS). Participants' safety will be monitored throughout the study.