Objectives: Inappropriate usage of antibiotics has been associated with bacterial antibiotic resistance. This study reported the medication behaviors and the knowledge of taking antibiotics for adults in Taiwan. Method: With random telephone dialing system, we interviewed adults aged 20 years and above to collect information of their sociodemographic characteristics, and knowledge and use of antibiotics. Results: Among 1507 adults interviewed, 1279 persons (84.9%) knew or had heard of antibiotics, and 548 persons (36.4%) and/or their children aged less than 18 years had taken antibiotics in the last six months. Knowledge scores of antibiotics increased among those with more education. Near 60% of respondents were self-reported non-compliant with physician's order to complete the entire medication course. Among those with antibiotics prescription in the last 6 months, 70.1% did not complete the medication if the symptom had become alleviative. Individuals who were more likely non-compliant with physician's order were those who had purchased antibiotics from drugstores with no prescription, compared with those with the prescription (94.5% vs. 66.9%) (p＜0.0001). However, there was no significant association between knowledge level and the inadequate antibiotics medication. Conclusion: Good knowledge does not assure of adequate medication. The challenge of achieving better compliance with antibiotics use among general population is more complex than just education.