An accurate and precise method was developed for the determination of carrageenan in milk-based infant formulas. Following digestion of protein with papain, carrageenan was precipitated with Hyamine 1622, a quatemary ammonium salt. The precipitate was washed to remove lactose, dissolved in sulfuric acid and the carrageenan assayed by color development with the phenol-sulfuric reagent. Filtrations and washings were facilitated with Millipore filters. Carrageenan recovery of spiked-formulas averaged 99.67% for ready-to-feed products and 95.74% for concentrated products, which respectively contained 7.1% and 14.2% lactose. To obtain these accuracies the reference carrageenan must be identical to the carrageenan in the product.