Changes in chlorophyll, carotenoid, ascorbic acid, and glutathione levels were determined during broccoli storage in 9 controlled atmospheres ranging from 0 to 10% O-2 and 2 to 20% CO2 concentrations. In low O-2 concentration, the level of glutathione decreased, whereas in high O-2 and low CO2 concentrations, the level of chlorophyll and ascorbic acid decreased significantly. A mixture of 2% O-2 and 4 to 10% CO2 was found to be optimum for simultaneous maintenance of pigments, ascorbic acid, and glutathione. Respiration models were developed as functions of storage time and O-2 and CO2 concentrations using a multiple regression analysis based on these gas compositions. When the modified atmosphere gas environment inside a broccoli package was simulated, an optimum gas condition of 2% O-2 and 5% CO2 was derived using a film having a 1,000 ml/day/atm O-2 transmission rate. Simulation result agreed well with experimental data.