Monthly variations of some physical and chemical characteristics of Sile waters at Assiut (373 km south from Cairo, Egypt) during the period from September 1980 to September 1982 were followed and discudsed. As expected, the maximum temperature was recorded in summer and the minimum in winter. The pH values of Xile waters were recorded to be in the vicinit,y of 8.0. The highest, oxygen concentrations were recorded in the summer mont,hs, mainly due to the relatively high photosynthetic activity. The total soluble salts and the t,otal alkalinity exhibited almost identical t.rends. Nitrate, phosphate, silicate and chloride concentrations showed no major regular trends. The cation abundances by weight were as follows: Ca?+ > S a + zMgZ+>K+.