This study indicates that a comparison of psychotic depressions of the manic-depressive group with normals shows in the former:1. The total fatty acids of the plasma are higher in the fasting state; also that after a fat meal there is a greater rise in the total fatty acids than in normal subjects.2. The cholesterol is at a higher level, both in the fasting state and after a fat meal. (See discussion.)3. The iodine number is lower in the depressives which can be taken to indicate that in these cases there is a greater proportion of saturated plasma lipoids.In conclusion we have to thank Dr. C. A. Porteous and Dr. E. C. Menzies of Verdun Protestant Hospital for the privilege of using some case material under their care.