Overwintering biology of Orius vicinus (Ribaut) (Hemiptera: Anthocoridae) was investigated between November 2017 and April 2018 in the Balcali location of Adana Province, Turkey under outdoor conditions. The duration of egg and nymphal development time, pre-oviposition, oviposition and post-oviposition periods of females, the number of eggs laid and adults longevity were determined by the experiments performed in the first day of each experimental month under the outdoor conditions at the Department of Plant Protection, Faculty of Agriculture, University of cukurova. The duration of egg hatching lasted between 5 and 10 days in all months of experiment and the tested eggs were hatched even at low temperature and under short day length conditions. More than half of the nymphs obtained from the tested eggs became adults in the winter months. Despite the nymph's survival was affected negatively by the sudden changes in temperature, they were tolerant to the low temperatures and short-day lengths during the winter period. All females in the trials oviposited for about 30 days even in the coldest periods (approximately 15 degrees C). The females were not affected by the environmental conditions particularly in winter season, and they did not undergo reproductive diapause. The obtained data shed light on the overwintering biology of O. vicinus which may be helpful for their potential role in controlling the non-diapaused pest species such as pest thrips in the early spring season.