The toxicity of sodium stearoyl lactylate (SSL) was examined in Wistar rats fed diets containing 0, 1.25, 2.5, and 5% SSL for one year, equivalent to mean daily intakes of 558, 1115, and 2214. mg/kg/day in males and 670, 1339, and 2641. mg/kg/day in females, respectively. SSL was well tolerated at these dietary levels as evidenced by the absence of toxicologically significant changes in the general condition and appearance of the rats, survival, neurobehavioral endpoints, growth, feed and water intake, ophthalmoscopic examinations, hematology and clinical chemistry parameters, urinalysis, or necropsy findings. The occurrence of uterine endometrial stromal polyps was the only finding of potential significance. Given the frequent occurrence of these benign tumors in rats, wide variability in the reported incidence of this type of polyps in rats, the lack of statistical significance and lack of biological evidence to suggest a mechanism for the slightly greater incidence in the groups fed 2.5 and 5% SSL, it was concluded that the endometrial stromal polyps observed in females fed SSL were not related to treatment. The no observed adverse effect level (NOAEL) of SSL was placed at 5%, the highest dietary level tested (equivalent to 2214. mg/kg/day for males and 2641. mg/kg/day for females). © 2010 Elsevier Ltd.