Background Fentanyl-induced cough (FIC) usually occurs after the intravenous administration of fentanyl during general anaesthesia induction. It is a transient condition depending on the fentanyl administration dose and injection speed. Oxycodone can also prevent FIC because it has been proven to treat coughing. This study aimed to evaluate the efficacy of different oxycodone doses to prevent FIC during general anaesthesia induction. Methods In a double-blind randomised controlled trial, 210 adult patients who were undergoing elective surgery, classified as American Society of Anaesthesiologists physical status I-II, and aged 20-65 years were randomly assigned into five equally sized groups: Sham group, Group ROMAN NUMERAL ONE, Group II, Group III and Group IV. Groups ROMAN NUMERAL ONE-IV were each intravenously injected with oxycodone 0.025, 0.05, 0.075 and 0.100 mg/kg, while an equal volume of normal saline was given instead of oxycodone in the Sham group. Five minutes later, fentanyl 3 mu g/kg was intravenously injected within 5 seconds, then, 2 minutes later the other drugs were administered for general anaesthesia induction. The occurrence and severity of coughing were observed within 2 minutes of the fentanyl injection. Vital signs and intensities of coughing were recorded and analysed. Results Coughing incidences were each 57.1, 50, 42.8, 33.3 and 21.4% in the Sham group and Groups ROMAN NUMERAL ONE-IV. Significant differences were found in the incidences of coughing between the Sham group and Groups III-IV. No significant differences in FIC incidences have been detected between the Sham group and Groups ROMAN NUMERAL ONE-II. However, no significant difference in FIC incidence existed between Group III and Group IV. Cough severities in Groups III and IV were significantly lower than in Groups ROMAN NUMERAL ONE and II (P < .05). No significant differences existed in the hypotension or severe bradycardia incidences during anaesthesia induction among the five groups (P > .05). Conclusion Oxycodone 0.075 mg/kg provided more effective FIC prevention during general anaesthesia induction.