Gold nanoparticles prepared via laser ablation in aqueousmicellar solution and by chemical method was studied under UV-light. The results showed that, no effect of light was observed on the nanosphere in micellar solutions. While in case of nanoparticles prepared by laser ablation in distilled water, the aggregations was observed. This may be due that the capping micelles prevent the nanoparticles from aggregation during the irradiation time courses. On the other hand the gold nanorods (Nds) of aspect ratios of L/d(length dividedwidth)= ï¾2.6, 3.1,3.6, and 3.8 with absorptionmaxima at 700, 730, 760 and 780nm, respectively, have been found to change their shape after irradiation. The rat of photodecomposition decreases with decreasing the aspect ratios. The critical photodecomposition was at aspect ratio of 2.3. The decreasing was explained in the dissolution of the surfactant around the gold nanorods.