Objective To evaluate the effects of combined use of dexmedetomidine (Dex) and azasetron in postoperative intravenous analgesia on postoperative nausea and vomiting (PONV) for female patients after lumbar fusion surgery. Methods A total of 180 female patients [aged 18‒65, BMI 18‒30 kg/m2, American Society of Anesthesiologists (ASA) status Ⅰ or Ⅱ] who were scheduled for posterior lumbar fusion surgery were selected. According to the random table number method, they were divided into three groups (n=60): a Dex and azasetron group (group DA), a Dex group (group D) and an azasetron group (group A). For postoperative analgesia, they were administered with Dex 1.5 μg/kg+azasetron 30 mg+sufentanil 2 μg/kg, Dex 1.5 μg/kg+sufentanil 2 μg/kg and azasetron 30 mg+sufentanil 2 μg/kg, respectively, before dilution in 100 ml with normal saline. The infusion rate was 2 ml/h. Then, these three groups were compared for the occurrence of nausea, vomiting and remedial anti‑emetics at postoperative 0‒6 h, 6‒12 h, 12‒24 h, 24‒48 h and 0‒48 h. The resting Visual Analogue Scale (VAS) score and Ramsay sedation score at postoperative 6, 12, 24, 48 h were recorded. Furthermore, the time of use of remedial analgesics and adverse reactions (such as hypotension, bradycardia, Ramsay sedation scores≥4, dizziness, headache, abdominal distension, constipation and rashes) within postoperative 48 h were observed Results Compared with group A, group DA showed significantly decreases in postoperative nausea at postoperative 0‒6 h, 6‒12 h, 24‒48 h and 0‒48 h, decreases in vomiting at postoperative 6‒12 h and 0‒48 h (P<0.05), and decreases in the times of use of remedial anti‑emetics (P<0.05), while group D showed increasing incidence of nausea and vomiting at postoperative 0‒6 h (P<0.05). Compared with group D, group DA showed significant decreases in the incidence of nausea at postoperative 0‒6 h, 6‒12 h and 0‒48 h (P<0.05), decreases in the incidence of vomiting at postoperative 0‒6 h, 6‒12 h and 0‒48 h (P<0.05) and decreases in the times of use of remedial anti‑emetics (P<0.05). There were no statistical difference in the resting VAS score, Ramsay sedation score and the time of use of remedial analgesics among the three groups at postoperative 6, 12, 24, 48 h (P>0.05). There were no statistical difference in the incidences of hypotension, bradycardia, Ramsay sedation scores≥4, dizziness, headache, abdominal distension, constipation and rashes among the three groups (P>0.05). Conclusions Low‑dose Dex and azasetron can be used in combination for postoperative analgesia to reduce the incidence of PONV in female patients after posterior lumbar fusion surgery, without additional adverse reactions.