Abstract: Quick decline disease causes collapse of healthy mango plants within a few days. The menace has been observed in the entire mango growing areas of Pakistan. The leaf samples of healthy and diseased mango plants of two major varieties viz. chaunsa and langra were analyzed to asses the variations in the contents of sugars, free amino acids and metals in relation to quick decline. In general, the contents of total sugars, reducing sugars, non-reducing sugars, free amino acids and minerals were found to be decreased in the diseased leaves as compared to that of healthy leaves of both the mango varieties. Quantitative analysis of macro and micro-nutrients was carried out by atomic absorption and flame emission spectrometry to find the status of these elements in healthy and diseased leaves. Mg contents were found to be decreased in the diseased leaves of both the mango varieties whereas Cu and Zn contents were found to be increased. No consistent trend was observed in case of other metals.