A comparative study of fully ventilated onion bulb storage structure, netted bag structure, mud coated structure and heap storage structure was conducted in Bahir Dar Institute of Technology, Ethiopia to determine their performances in extending the shelf life of onions. Collected fresh Bombay red variety onions were field cured at Bahir Dar institute of technology for 8 days by sun curing method. Cured onions were stored in specified storage structures for 90 days. The experiment was conducted in single factor (storage structure) with four levels and three replications. The data on physicochemical parameters (Sprouting percentage, rotting percentage, mould incidence, moisture content, colour change, ascorbic acid content, dry matter, firmness and percentage of marketable bulbs) were collected for 90 with 10 days interval including the first day. Hourly temperature, relative humidity and air velocity of ambient and storage environment were recorded continuously. Data were analyzed by using the SAS 9.2 version, the Analysis of Variance was conducted and mean comparison was done. Sprouting % of 97.47, 1.03, 1.19 and 1.33 was observed in heap storage, fully ventilated, netted bag and mud coated Storage structure, respectively by 90th day of storage. Similarly, Rotting % of 75.53, 1.81, 2.30 and 3.08 recorded in heap, fully ventilated, netted bag and mud coated storage structures, respectively on the 90th day of storage. Mould incidence % of 78.71, 2.73, 3.02 and 3.47 observed in onions stored in heap storage, fully ventilated, netted bag and mud coated storage structures, respectively on 90 days of storage. Marketable bulb % of 1.8, 73.41, 65.36 and 61.55 was observed for onions bulbs stored in heap, fully ventilated, netted bags and mud coated storage types, respectively after 90 day of storage. By the 90 days of storage, ascorbic acid content of 2.58, 5.71, 5.20 and 5.11 mg/100g was observed in onions stored in heap storage, fully ventilated, netted bag and mud coated storage types, respectively. Less percentage of sprouting, rotting, fungal incidence and higher percentage of marketable bulbs was recorded for onion stored in fully ventilated storage structure, it can be concluded that, the best method for the storage of onion in Bahir Dar area is fully ventilated storage structure and the next choice is netted bags.