For a generic drug, the quality of the active ingredient takes on great importance. Almost 90% of essential drugs contained in the WHO Model List are off-patent and available in generic form. Raw materials can also be generic, and their cost can vary considerably depending on labour costs, quality of the facilities, reputation of the supplier, quality and purity processes applied to the material. Professional judgement must be exercised in the purchase of such materials because compliance with pharmacopoeial specifications may not necessarily indicate good quality. The price of the raw material often represents more than 50% of the industrial cost price of a generic, which may lead manufacturers to target a lower quality raw material in their efforts to offer competitively attractive prices.