Objectives: The purpose of the study is to assess the effect and safety of spinal anesthesia with a mixture of low-dose Marcain and Fentanyl for caesarean delivery. The study is conducted on 485 pregnant women with cesarean delivery (minimum age is 17, oldest is 44, the lowest weight was 44 kg, the highest weight is 81 kg) by methods of spinal anesthesia with Marcain 0.5 percent low dose 0.15 mgfkg body weight combined dose of Fentanyl 25ug/kg body weight, in Kien An hospital - Hai Phong. Results: The level of blocking enough pain killers to pregnant women during surgery. Proportion of pregnant women achieving better effective anesthesia is 86.2 percent, effective anesthesia achieve satisfactory level is 10.5 percent. Only 3.3 percent of pregnant women do not achieve effective anesthesia. The average of standby time inhibits pain is 5.23 + or - 6.54 minutes, the shortest is 2 minutes, the longest is 7 minutes. The average of effective inhibit - time for a pain sensation is 135.27 + or - 9.1 minutes, the shortest is 50 minutes, the longest is 210 minutes. This time period is acceptable. To ensure the safety of hemodynamically for pregnant women during and after surgery. Ensure safety for children: 100 percent of the children were normal (Apgar score = 810) at 10 minutes after the birth. Some unwanted effects of drugs during and after surgery such as nausea, vomiting, chest pain, chills, itching, urinary retention, headache, but with low rates, from 2.2 percent to 15.4 percent. Condusions: Low-dose Marcain 0.15 mgfkg body weight combined dose of Fentanyl 25ug/kg body weight is suitable with spinal anesthesia for cesarean delivery.