The accelerated stability tests of preservative solutions in polyethylene (PE) and glass bottles were studied. Phenylmercuric nitrate, was found to be the most stable in PE and glass bottles. Methylparaben, thiomersal and chlorocresol were bound to be stable in order. In autoclave sterilization, it was shown that the highest loss occured in chlorhexidine gluconate, thiomersal and phenylmercuric nitrate followed by PE bottles. The losses of preservatives in glass bottles were not significant. The change of pH value of preservative solutions was also investigated during the test. It was found that for methyl paraben, the change in pH was within its stability limits but for thiomersal, the pH was found to be and might be responsible for its loss in PE and glass bottles. The change of pH was not significant for phenylmercuric nitrate but high for chlorocresol.