The effect of subchronic administration of morpholine oleic acid salt (MOAS) was studied in B6C3F1mice. The dose levels of MOAS used were 0%, 0.15%, 0.3%, 0.6%, 1.25%, and 2.5% in drinking water. Reduced weight gains were noted in both sexes in the 2.5% group as compared to controls, but reductions were not significant. Water consumption values showed a dose‐related tendency for a decrease in both females and males. Urine analysis showed significant elevation of specific gravity in the males in the 0.6%, 1.25%, and 2.5% groups and the females in the 1.25% and 2.5% groups. Significant elevation of plasma urea nitrogen was observed in males of the 1.25% and 2.5% groups and in females of the 0.6%, 1.25%, and 2.5% groups. The relative weight of the kidneys showed a dose‐dependent increase that was statistically significant for the 1.25% and 2.5% MOAS groups in both sexes. Except for cloudy swelling of the proximal tubules of the kidneys in mice on the 2.5% regimen, no treatment‐related histopathological alterations were observed in organs of either sex.