Thirty-three patients of Glanzmann's thrombasthenia (GT) and their families were assessed for the expression of alphaIIbbeta3 on platelet surface, by flow cytometry, to determine the common subtypes in North Indians as well as to assess the carrier status in family members of GT patients. GT was diagnosed in patients with bleeding manifestations accompanied by absent/reduced platelet aggregation, secondary to adenosine-di-phosphate, adrenaline, arachidonic acid and collagen. Based on alphaIIbbeta3 levels, 21 patients (64%) were classified as type I (as alphaIIbbeta3 was absent), 4 patients (12%) as type II and 8 patients (24%) as type III. Eight out of 20 fathers, 10 out of 20 mothers and 20 out of 31 siblings were found to have reduced alphaIIbbeta3 levels. Reduced alphaIIbbeta3 expression was seen in 63% of parents and 65% of siblings. It is possible that low alphaIIbbeta3 levels in family members may reflect their carrier status. It is postulated that flow cytometry estimation of alphaIIbbeta3 in parents/siblings may detect carrier status in GT. It is also revealed that type I GT is the commonest subtype in North Indians.