After initial screening for gestational diabetes, 182 3-hour OGTTs in altogether 168 patients with determination of plasma glucose at 30-minute intervals were performed. Two-hour and 3-hour areas below the curve were calculated. Twenty-two patients had a reduced glucose tolerance test as judged by the 3-hour areas. Twenty of the 22 patients had a reduced glucose tolerance even according to the 2-hour areas. The correlation coefficient between the 3-hour areas and the 2-hour areas was 0.97. In 160 observations plasma glucose and capillary blood glucose were compared. The correlation coefficient between plasma glucose and capillary blood glucose concentrations was 0.99. It is concluded that the discriminatory power of the 2-hour OGTT with capillary blood glucose determinations is comparable to that of the 3-hour OGTT with venous plasma glucose determinations. The simplicity of the suggested method makes it suitable for use in instances with moderate or small laboratory resources.