The purpose of this study was to provide the correct knowledge on GDM(Gestational Diabetes Mellitus) to nurses for effective care of pregnant women with GDM by investigating the knowledge of nurses about GDM. The subjects of this study were 557 nurses who work at six general hospitals in Seoul and Gyung-Gi province of Korea. The data were collected from November, 2000 to December, 2000, using a 30-item knowledge questionnaire about GDM consisted of eight areas developed by Choi et al. (2000): characteristics and diagnosis, influence on pregnancy, goal and method of management, diet therapy, exercise therapy, insulin therapy, hypoglycemia and hyperglycemia and postpartum care of GDM. The data were analyzed by SAS program for t-test, ANOVA and Scheffe test. The results were as follows: 1. The mean score of knowledge on GDM was 23.18. 2. There were significant differences according to age(p= 0.002), education background (p= 0.045). working period(p= 0.000), working unit(p= 0000), working experience of obstetric and gynecologic (OS & GY) units(p= 0.000), experience of pregnancy (p=0.003) and experience of delivery (p=0.014) in GDM knowledge. 3. The level of each area on GDM knowledge was as follows; 1) Area of characteristics and diagnosis of GDM The mean score of this area was 0.79. Nurses' knowledges were significantly different by age(p=0.003), marital status (p=0.018), working period(p=0.002) working unit(p=0.007), working experience of OB & GY units(p=0.005), experience of pregnancy(p=0.034) and experience of delivery(p=0.033). 2) Area of influence on pregnancy The mean score of this area was 0.93. Nurses' knowledges were significantly different by age(p=0.006), working unit (p=0.000) and working experience of OB & GY units(p= 0.000). 3) Area of goal and method of management The mean score of this area was 0.70. Nurses' knowledges were significantly different by age(p=0.004), region(p=0.006), education background(p=0.013), marital status(p=0.007), working period(p=0.000), working unit(p=0.011), working experience of OB & GY units(p=0.002), experience of pregnancy(p=0.025) and experience of delivery(p=0.043). 4) Area of diet therapy. The mean score of this area was 0.74. Nurses' knowledges were significantly different by age(p=0.002), region(p=0.011), marital status (p=0.001). working period (p=0.007). working unit(p=0.002), working experience of OB & GY units(p=0.001), experience of pregnancy(p=0.001), experience of delivery(p=0.011) and diabetes patients in family members(p=0.032). 5) Area of exercise therapy. The mean score of this area was 0.83. There were not significant differences in all general characteristics. 6) Area of insulin therapy The mean score of this area was 0.61. Nurses' knowledges were significant differences by age (p=0.024), marital status (p=0.048), working period(p=0.027), working unit(p=0.002), working experience of OB & GY units(p=0.000), experience of pregnancy (p=0.047) and experience of delivery(p=0.040). 7) Area of hypoglycemia and hyperglycemia. The mean score of this area was 0.83. Nurses' knowledges were significantly different by marital status (p=0.027), working period(p=0.001). experience of pregnancy(p=0.020) and experience of delivery(p=0.010). 8) Area of postpartum care The mean score of this area was 0.69. Nurses' knowledges were significantly different by working unit(p=0.000), working experience of OB & GY units (p=0.000) and working experience of medical unit(p=0.047). The results of this study are suggested that nurses might be taught systemically and individually about GDM so that they can become more proficient in detecting and preventing GDM, and therefore they will feel confident to teach GDM to women.