OBJECTIVES: Large seasonal variations concerning the prescription of antibiotics for systemic use (ATC group J01) in the outpatient sector may be a sign of overuse regarding virus infections. The aim of this study is to analyse those seasonal variations in Austria. METHODS: The data comprise all filled prescriptions at the expense of the 19 statutory health insurance funds in Austria, covering more than 97% of the national population. Observation period lasts from 2013 to 2015, on a quarterly basis. The main measure of antibiotic use is the number of persons to whom at least one antibiotic drug has been prescribed. Additionally, analyses were conducted regarding patient age as well as antibiotic subgroups. RESULTS: The highest number of patients was observed in the first quarter of every year, followed by the fourth and the second quarter. Thus, 10.0% of the population received an antibiotic in 2013/Q3, while in 2013/Q1 the share amounted to 15.3% - this represents a fluctuation of 53%. In 2014 and 2015 the respective fluctuations were 34% and 63%. Variations were especially high among the youngest cohorts (age 0 to 9 years) – with up to 99%. Looking at the number of prescribed medication packages of the subgroups, fluctuations were highest for macrolides, lincosamides and streptogramins (J01F), with 58% more packages being prescribed in winter 2014/15 (2014/Q4, 2015/Q1) than in the previous summer (2014/Q2, 2014/Q3). The respective increase for cephalosporins (J01DB/DC/DD/DE) was 34%, and for penicillins (J01C) 32%. CONCLUSIONS: Compared to other European countries, Austria has a relatively low overall antibiotic use. Nonetheless, the seasonal variations are high. This might be an indicator for suboptimal use of antibiotics. As this is a growing public health concern, the use of antibiotics in the Austrian health system should be considered carefully by doctors as well as patients.