Yes, casein protein powder is a complete protein, meaning it contains all of the essential amino acids in sufficient amounts. It is derived from milk and is one of the two primary proteins found in milk, the other being whey. Casein is a slow-digesting protein and is often used as a dietary supplement, particularly before bedtime, as it can provide a sustained release of amino acids to the muscles during sleep. However, like all proteins, the specific amino acid profile of casein protein powder can vary depending on the source of the milk and the processing methods used.