This research was conducted at the Laboratory of Animal Products Technology, Faculty of Animal Husbandry, Islamic University of Malang. The research was date 7 May to 7 July 2020. This study aimed to analyze the effect of giving red guava juice on the pH value of milk yogurt and the lactic acid levels of goat milk yogurt. The materials used were 2.5 liters of pure Ettawa crossbreed goat milk and 300 ml of red guava juice (Psidium guajava L). The starter used was a commercial powder starter containing Lactobacillus Bulgaricus and Streptococcus Thermophillus bacteria. The method used was experimental with a completely randomized design method (RAL) consisting of 4 treatments with 5 replications. P0 = Yogurt without the addition of red guava fruit extract, P1 = 10%, P2 = 15%, P3 = 20%. The analysis of variance showed that giving red guava juice with various concentrations had a very significant effect (P <0, 01), on the pH value of goat milk yogurt. The average pH value of goat milk yogurt with the addition of red guava juice is P0 = 4.46, P1 = 4.22, P2 = 4.20 and P3 = 4.16. And the analysis of variance showed that giving red guava juice with various concentrations had a very significant effect (P <0.01) on the lactic acid levels of goat milk yogurt. The average lactic acid levels of goat milk yogurt with red guava juice were P0 = 1.21%, P1 = 1.78%, and P2 = 1.65% and P3 = 2.06%. Red guava affects the pH value and lactic acid levels of goat's milk yogurt, the higher the concentration of the addition of red guava juice, the relatively lower the pH value and increase the lactic acid levels. The best concentration of addition of red guava juice with a concentration of 10-15%, research is needed on the effect of giving red guava juice on the number of microbes, orgonoleptic test, antioxidant test and nutritional content test of goat milk yogurt. Key word: Goat milk, yogurt. Red guava, pH value and lactid acid level