Abstract A new technique, a modification of the Cutler, is presented for determining erythrocyte sedimentation rate; it is based on the fundamental fact that it is the size of the rouleaux that determines the rate of settling. This technique is precise, simple, and time-saving. The results are easy to interpret and need no correction for anemia. The method embodies principles that are applicable to all tubes. The essential features are as follows: Cutler sedimentation tubes of 1 c.c. caapcity are used, graduated into 50 mm. divisions, with 0 at the 1 c.c. level. One-tenth cubic centimeter of 3.8 per cent sodium citrate solution and 0.9 c.c. of blood obtained by puncture of a suitable vein are gently mixed in a 2 c.c. syringe and poured into the sedimentation tube, and the tube is placed in a special rack. The position of the sedimenting column of erythrocytes is determined every five minutes for one-half hour and is recorded on special charts. The maximum settling in any five minutes during the half hour is the sedimentation rate and becomes the unit of comparison. For all practical purposes a maximum settling in five minutes of 1 mm. or less is normal. Everything else is abnormal and therefore pathologic. Generally speaking, maximum rates in five minutes between 1.5 and 4 mm. indicate disease of slight intensity; rates of 5 to 9 mm. indicate moderate intensity, and rates of 10 mm. or more, marked intensity. Evidence is presented that the 1 c.c. Cutler tube is a practical tube for sedimentation rate determination, giving reliable and accurate results under average conditions. This tube appears suitable for standardization of technique.