The use of human milk in milk banks requires thermal processing to eliminate microbiological hazards. An evaluation is made of the stability of overall human milk bactericidal capacity following 2 modalities of thermal pasteurization: 63 degrees C/30 minutes and 75 degrees C/15 seconds. Ten milk samples (mature milk) were analyzed. In each sample, the effect of both thermal treatments on bactericidal capacity against Escherichia coli was evaluated in relation to the capacity of fresh milk (control). All the samples analyzed possessed bactericidal capacity. Human milk pasteurization induced a significant loss of this capacity that was more pronounced after high-temperature treatment than after low-temperature processing. Untreated milk, low-pasteurized milk, and high-pasteurized milk yielded a reduction in E. coli growth of 70.10%, 52.27%, and 36.39%, respectively. In conclusion, human milk possesses antimicrobial activity that is lost in part as a result of thermal processing. Such bactericidal capacity is, moreover, better preserved by low-temperature, long-time pasteurization.