This study aims to search the effect of flipped classroom on students' learning a new grammar structure and their attitudes towards the English course. The study was carried out for 6 weeks with 56 students studying in five different preparatory classes at a black sea region university's foreign languages school in the fall term of 2015-2016 academic year. The design of the study was 'non-equivalent control group design' which is one of quasi-experimental designs. Data were gathered with help of an achievement test and an attitude scale. Flipped classroom model was applied in the experimental group while traditional instruction was applied in the control group. At the end of the study, it was concluded that flipped classroom had medium effect on students' academic achievements and attitudes comparing to traditional instruction.