Comparative investigation of the components and characteristics of three types of fully developed granular sludges operating in full-scale and laboratory upflow anaerobic sludge blanket reactors under different conditions was qualitatively and quantitatively carried out. Extracellular polymeric material of granular sludges contained 1.7-2.7% carbohydrates, 2.5-5.1% nucleic acids and 8.3-16.3% proteins of total suspended solids (TSS). The ash content of the granular sludges varied from 11-21% and was an equal combination of metals-mainly calcium, sodium, magnesium, potassium, phosphorus and iron-and non metals in the form of day. The results indicated that feed mineral concentration had an overall effect on the mineral composition of granular sludges and that specific uptake of preferred minerals such as magnesium, iron and phosphorus occurred depending upon the operational and environmental conditions. Significant variation was found in the dominant methanogenic groups.