In foods treated in various ways for their preservation, microorganisms that can resist conditions that the great majority of micro-organisms cannot withstand, occasionally develop and bring about undesirable changes. These changes are common in foods that have been subjected to heat and are the results of the presence of organisms that have the ability to resist temperatures that usually effectively sterilize the product in question. In sweetened condensed milk, which is presumably preserved by the addition of high percentages of sucrose, abnormal changes sometimes occur as a result of the presence of organisms that have the ability to develop in sugar concentrations that most organisms cannot withstand. The present paper deals with an outbreak of gas production in sweetened condensed milk.