Majority of the mosquito repellents used in the recent years constitutes a variety of essential oils and plant based repellent formulations. Essential oil based mosquito repellents are known for their environmental suitability, while synthetic mosquito repellents are degraded because of their toxic effects to environment and humans as well. Owing to the unavailability of natural anti-mosquito formulations, synthetic mosquito repellents were introduced commercially. The purpose of this study is to identify chemical compositions of various commercially available mosquito repellents and their associated hazards. The efficiency of these repellents is discussed in view of other factors such as, efficacy ratio, effectiveness, biodegradability, and availability. Major components of various essential oils are analyzed by the results obtained from gas chromatography (GC). Numerous components present in mosquito repellents are injurious to human health. U.S Department of Defence has also issued maximum concentration limits for repellent chemicals. The standards listed by World Health Organization (WHO) are undeniable.  The aim of present study is to identify various chemicals that exhibit strong mosquito repellent characteristics and to analyze their suitability in view of associated environmental aspects. Rapid volatility, less protection time and thermal instability are the key factors which should be addressed by a mosquito repellent. Current study lays down groundwork for the synthesis of new mosquito repellents which are viable commercially as well as environmentally. Need for replacing toxic synthetic repellents by essential oil based repellents and new environmental friendly chemicals are emphasized.