After coronary illness and all malignancies stroke is the third basic reason for death on the planet.study was aimed to determine the possible relationship between mean corpuscular volume and thrombotic stroke in young people. The study was carried out at a tertiary care hospital. The case-control study was done in 50 patients of young thrombotic cerebrovascular disease and 50 healthy age  and sex-matched controls. Estimation of MCV levels was done in both the groups and compared. The mean age  of cases was 41.56 ± 9.51. total of 50 cases of young stroke, 36 (72%) was male. The mean and SD values of MCV levels for the case group were 96.78±7.54, for the control group were 82.07±7. Out of the 50 young stroke patients, 17 (34%) had MCV levels ≥101fL. In the control group, all the subjects had MCV levels ≤ 100fL. The mean haemoglobin level was 14.29, with SD ± 1.48 in cases, and the control group mean haemoglobin level was 12.41 with SD±1.39. Mean serum haemoglobin levels were higher in cases than controls. The Significant Macrocytosis (MCV≥100fL) can be a new, low cost and early marker in anticipating the risk of developing thrombotic stroke in young adults who may or may not have anaemia.