The halal industry is still in its early stages of development, and efforts to chart the way forward in compliance with Islamic principles are desirable and necessary. As with Islamic banking in the early years, this industry has also been largely driven by market demands and realities. It would be advisable to enrich the achievements of the halal industry with research efforts that advance a better understanding of Islamic principles and the scientific knowledge relevant to our concerns. The article begins with a review of evidence in the Qur'an and hadith on the halal or mubah, and then proceeds to address the haram. The later part of the article covers the reprehensible (makruh) and the recommendable (mandub) respectively, as well as fiqh and the relationship between Islam and science.