Background: The misuse of antibiotic treatment is an important cause of emerging bacterial resistance. Taking antibiotics without prescription through self-medication, friends or relative opinions, or pharmacist advice is a very common behavior in the developing countries. Methods: The sample was selected from the most important and most populated area in Saudi Arabia (Riyadh region). The data were collected through self-administered questionnaires for educated participants and with interviewers for non-educated participants. The participants were selected randomly from outpatient attendants of hospital and health centers. The data were analyzed using SPSS software program, with descriptive and inferential statistics. Results: The response rate was 96% with mean age of 32 ± 12.79 years, ranging from 14 – 80 years. Male subjects were a little more than females. Most of these subjects were university students. About 73% were not health staff and approximately 70% of subjects reported that they had health insurance. Most subjects (65.7%) took the antibiotics based on specialist prescription. For those who took their drugs without prescription, around 67.2% reported that was because they used it before. Following doctor's instructions about the time of taking the drug was reported by 80.3% of subjects. Following doctor's instructions regarding the appropriate dose was reported by 88% while, taking all the prescribed doses was only reported by 56% of the subjects. Significant association was found between health insurance and the way the subjects take their drug. Also, significant associations were found between education and income with following the doctor's instruction regarding taking all doses. Conclusion: Misuse of antibiotic is still higher. There is extremely need for public educational programs in addition to application of the laws.