Recently all-trans retinoic acid, an oxidation product of retinol, has become famous, since it is a component of "retinoids solution" of "Di Bella's therapy". Since all-trans retinoic acid is rapidly destroyed in the presence of light and oxidants, we verified its stability in samples of "retinoids solution" stored in conditions believed optimal (under stream of nitrogen) and we compare the obtained results with those observed in other "retinoids solution" samples daily open and close again, simulating the intake from the patient. All samples showed a decrease of all-trans retinoic acid recovery at the end of the study, with a more rapid decline in samples daily open. From our observations, we decided to indicate an expiration date of one months from the date of "solution" preparation. The patient's manipulation brings out a change in the final composition of "retinoids solution".