The amount of ultraviolet radiation(UVR)reaching the Earth’s surface has been increasing as aresult of an increasingly thinner ozone layer.The UV-A component of the UVR is able to generate oxidative
stress in the compound eye and haemo lymph of Procambarus clarkii when the latter was exposed for as little as 15min daily for one week to UV-A.Changes in the eye involved corneal material, crystalline cones, pigments in cones talks and retinula cells, rhabdom integrity, haemocyte in filtration,and haemal spaces. UV-A had significant impacts on haemolymph iron and glucose, where as Ca ions were unaffected.Total Protein and Cu ions showed on lyin significant changes following UV-A radiation.Involvement of lipid peroxidation and DNA fragmentation was significant with regard to the tissue damage cause by the UV-A.UV A further more induced biological effects on serum electrophoretic patterns: some fractions either increased in size or others decreased. The described change scan be used as reference guide lines in evaluations of UV-A induced stress effects in P. clarkii