Samples of goat milk with low and high alpha S1-casein content collected from animals of Alpine and Saanen breeds in the same stage of lactation were compared for coagulation properties (coagulation time, rate of curd formation, curd firmness) and chemical composition (total solids, ash, total protein, total casein, whey protein, fat, Ca, P, pH). Milk with low alpha S1-casein had a faster coagulation time, whereas milk with high levels produced the firmer curd associated with a better chemical composition. Within high alpha S1-casein milk, comparison between breeds showed milk from the Alpine breed had significantly better coagulation properties than that from the Saanen breed. Milk composition accounted for 27% of the variation in coagulation time, 21% of variation in cured formation rate, and 54% of variation in curd firmness.