Muslim countries import different kinds of products from non-Muslim countries. On the other hand however, goods are exported to rather than imported from Muslim countries. Common among these products are cosmetics many of which contain najs (impure), harmful or poisonous ingredients which have been transformed during production. The research will set the shari'ah conditions governing the istihalah in these products. The study is conducted using the qualitative methodology in which the researcher collects relevant data from reliable sources and then study it using content analyses. The researcher found the following results: The legal conditions for Istihalah with respect to cosmetic products are as follows: 1.The najs substance in the contents of the products must have been converted into a material different from its former original nature; 2. The najs substance in the product must have been transformed or displaced completely such that no trace of it remains in the product after the transformation; 3. If the najs material is not completely displaced then the use of the product is subject to the condition of existence of necessity and compelling need for the product such as using it for medication in the absence of lawful alternative and upon the prescriptionof a trusted Muslim doctor with requisite medical knowledge; 4. There must be overwhelming belief in its usefulness which is based on the clearance of a trusted Muslim doctor; 5. Fragments of najs materials contained in cosmetics which have not been transformed shall not be used in situation of necessity or need for the purpose of oral consumption (eating and drinking) or even bodily application; 6. The products must not be harmful for human consumption even if its ingredients have been transformed.