Nanoparticles of noble metals like silver and gold were synthesized by laser ablation technique;the metal target is immersed in double distilled and deionised water DDDW.Nd: YAG pulsed lasers (Q-switched, 1064 or 532nm doubled frequency) is used. The optimum preparation parameters were: laser shots of 80 pulses, laser energy of350mJ, liquid depth of 8mm, laser fluence of20mJ/cm2, laser wavelength for ablation 1064nm and laser wavelength for irradiation 532nm. The efficiency of ablation and irradiation processes was quantified in term of UV-Visible absorption peak height.UV- Visibleabsorption spectra show a single peak around 400nm for silver NPs and 525nm for Au NPs indicating their production.In the same way, the effects of laser shots, energy, wavelength, aging time, distance, temperature and ultrasonication were studied. The concentration of prepared NPs was determined using Atomic Absorption Spectrophotometer technique (AAS). Transmission electron microscopy (TEM) technique was used to show the shape and size distribution of the prepared NPs which showed that all NPs were of spherical shapes and the average size of Ag NPs was 20nm, for Au NPs the average size was 25nm and for Ag-Au composite NPs the average size was 35nm.Formation Ag-Au NPs was done using laser ablation of gold target in Ag NPs solution with same preparation parameters. Then the Au-Ag composite NPs formed by irradiation of Au-Ag NPs mixture using pulsed Nd-YAG laser, λ=532nm. Novel bimetallic of Au–Ag core-shell nanoalloys was checked by TEM. It appears to be nearly spherical. Crystal structure, roughness and particle size of the prepared NPs were studied using X-ray and Atomic Force Microscope(AFM) techniques. Effects of the prepared NPs on serum Alpha amylase and alkaline phosphatase were studied. It shows that Ag NPs inhibit the Alpha amylase enzyme, while Au NPs, Au-Ag mixture NPs and Au-Ag composite NPs activate the Alpha amylase enzyme. The effects on alkaline phosphatase show activation with Au NPs but Ag NPs and composite NPs inhibits the alkaline phosphatase enzyme.