Abdominal and transvaginal ultrasound examination in the first trimester of pregnancy confirm the situation of pregnancy intrauterine or extrauterine, the age of pregnancy and the viability.If the examination is performed very early in the first trimester the result will be not definitive. Objective:to determine the most proper age of pregnancy of ultrasound examination in order to confirm the situation of pregnancy, the age of pregnancy and the viability. Method:We included in the study 720 women who performed the ultrasound examination not more than 84 days from the first day of rthe last menstrual period.We studied the relationship between the age of pregnancy at the time of examination and the results of examinations for situatin and viability of pregnancy. Results:If the ultrasound examinations were performed before 35 days of pregnancy,the results were not definitive; if the ultrasound examinations weres performed between 35- 41 days of pregnancy,there was only the confirmation of situation but not of the viability; if the ultrasound examination was performed after 49 days of pregnancy the results were definitive for the viability. Conclusion: To decide the viability of pregnancy, the right time for the first ultrasound examination is after 49 days from the first days of the last menstrual period.This will reduce unecessary ultrasound examinations.