Abstract: Objective To examine the influence of social demographic characteristics on antibiotics use among middle aged and elderly people and to provide evidences for making health intervention strategies.Methods The participants(2 566 urban and rural residents aget 45-74 years)of a questionnaire survey were selected with multi-stage random sampling from communities in Gansu province.SAS 9.1 software was used in data analyses with applications of multiple logistic regression and stepwise logistic regression.Results Antibiotics were reserved by 63.69%of the respondents in their homes and self-medication was practiced by 42.72%of the respondents.The antibiotic use was stopped immediately by 35.49%of respondents once they had attenuated symptoms.The top three correct antibiotics use behaviors were storing antibiotics in a cool,dry place(77.54%),taking antibiotics without tea or drinks(64.09%)and taking the antibiotic strictly according to the doctor's advice(53.95%)among the respondents.Antibiotics for self-medication of urban respandents were less than those of rural respondents(odds ratioOR=0.56).In addition,the urban respondents were less dependent on commercial advertising(OR=0.71),much more careful to correct storage of the antibiotics(OR =2.42),less dependent to doctor's advice(OR=0.73)and less likely to take the antibiotics via intravenous drip(OR=0.78).The respondents with junior middle school or lower education were more likely to rely on commercial adventisement(OR=1.72)than those with senior high school education and had less correct knowledge about the storage of antibiotics(OR=0.48),less compliance with the doctors' advice(OR=0.71 for medication frequency,OR=0.73 for medication dosage),and were more likely to take antibiotics with tea or drinks(OR=1.66).Male respondents were less compliance with the doctors advice(OR=0.75 for medication frequency,OR=0.76 for medication dosage)than female respondents.The respondents with family monthly income less than 1 000 RMB Yuan were more likely to take antibacterial drugs with tea than the respondents with the income of 2 000 RMB Yuan(OR=1.39).Conclusion Unreasonable antibiotics usage is common in middle aged and elderly people.Further health promotion must be emphasized in the residents living in rural areas,with low education and low income.