Background: Hyperemesis gravidarum is known as a complex disease with interaction of biological, psychological and sociocultural factors. Our study was an attempt to understand the psychological effects on hyperemesis gravidarum by using an objective scale. Methods: Thirty-four pregnant women with hyperemesis gravidarum who were hospitalized in the Obstetrics and Gynecology Department of Dr. Lutfi Kirdar Kartal Education and Research Hospital in Istanbul, Turkey comprised the patient group and asymptomatic pregnant women who came for routine antenatal visits to our clinic were enrolled in this study as the control group between March 1, 2007 and October 15, 2008. Women in both groups filled in the Symptom Check List (SCL-90-R) questionnaire. The data collected from both groups were analyzed by using the Student’s t-test (SPSS 13.00). Frequencies of high SCL scores between groups were analyzed by chi-square tests. Results: The patients with hyperemesis gravidarum had higher distress scores than those in the control group. The mean value of global severity index (GSI) was 1.03 in the patient group and 0.64 in the control group. The difference was statistically significant (p < 0.005). The most significant difference between the two groups was in somatization subscales (p < 0.0001). Conclusion: Hyperemesis gravidarum is a complex disorder with psychological aspects. Considering this fact can help us deal with the disorder.