Sour cherry (Prunus cerasus L.) variety 'English Morello' fruits were stored for up to 20 days at 2degreesC in air or controlled atmosphere (CA) consisting of 25% CO2 + 10% O-2, 15% CO2 + 10% O-2,or 5% CO2 + 10% O-2. The effects were compared on decay, juice optical density, titratable acidity, pH, soluble solids content and firmness. CA treatment has a great potential for sour cherry storage in maintaining quality and in extending the length of the storage period. The study has indicated that the decay of sour cherry can be greatly reduced by 25% CO2. High CO2 concentration gave the best retention of red colour and titratable acidity throughout the storage period. Fruit juice optical density and firmness increased with storage time. Fruits stored in 25% CO2 + 10% O-2 had higher soluble solids content compared with fruits stored in air.