In 1999-2000 at the Medical Clinic Motol Faculty Hospital in collaboration with the Gynaecological Clinic of the Hospital a group of 55 pregnant women with the diagnosis of gestational diabetes (GDM) were followed up. The objective of the investigation was to find out how in the investigated area (detachment area of the Gynaecological and Obstetric Clinic Motol Faculty Hospital) GDM is diagnosed at present, how it is treated and what is the percentage of perinatal morbidity in the investigated group. The mean age of the investigated women was 32.3 +/- 4.5 years. The presence of risk factors for the development of GDM was found in 59.8% of the examined women. 65.7% women had a positive gynaecological case-history. GDM was detected most frequently during the 30th week of pregnancy, in 25% women in the 35th and later week of gestation. In 52% the diagnosis of GDM was established only on hospital admission on account of complications of pregnancy. The mean HbA1C level during detection of gestational diabetes was 6.81 +/- 0.41%. The majority of women -91.1%--were treated by diet, 8.9% women had insulin treatment. The prevalence of diabetic foctopathy was 48.3%. The mean weight of the offspring of diabetic mothers was 3350 g +/- 248 g, the mean length was 49.6 +/- 6.3 cm. No stillbirth was recorded. One infant suffered from an inborn developmental defect (morbus Down). The results provide evidence not only of late diagnosis of GDM (after the 28th week of gestation) but also of inadequate screening in the field, as GDM is frequently detected only during complications of pregnancy.