Soy yoghurt is a fermented soymilk products. The fermentation process by Lactobacillus bulgaricus and Streptococcus thermophillus change the content and composition of bioactive compounds, such as phytosterols. The aims of this study is to evaluate the colorimetric method to quantify the total phytosterols content in soybean, soymilk, and soy yoghurt. The procedure was based on the colored products of phytosterols with Liebermann- Buchard reagent. The method was evaluated for linearity, accuracy, precision, limit of detection, and limit of quantification. The procedure meets the validation criteria. Colorimetric method is a valid procedure to determine the total phytosterol content in herbal derivatives.