Objectives To determine whether initial vital signs correlate with the amount of haemoperitoneum in patient with ruptured ectopic pregnancy presenting to accident and emergency department. Method A retrospective study in a regional public hospital in Hong Kong. We retrospectively collected data of all patients with the diagnosis of rupture ectopic pregnancy (ICD-9-CM 633) from the period of January 2006 to December 2007. Demographics of the patients, gestational ages, triage vital signs (pulse rate and blood pressure), emergency department ultrasound record and operation record were reviewed. Mean arterial pressure and shock index were calculated accordingly. Different vital signs were used to correlate with the amount of haemoperitoneum by using Pearson correlation analysis. Results Ninety-three patients with ruptured ectopic pregnancy were recruited. Mean age of patients was 30 years (range 17-47, ±6 SD). Mean week of gestation was 6.7 week (range 3-12, ±2 SD). Forty-two patients (47%) had intraperitoneal free fluid shown in emergency department ultrasound scan. Pearson correlation coefficients between vital signs and amount of haemoperitoneum were: systolic blood pressure (-0.44, p<0.001), diastolic blood pressure (-0.24, p=0.01), mean arterial pressure (-0.37, p<0.001), pulse (0.18, p=0.05) and shock index (0.45, p<0.001). Conclusion None of the vital signs showed good correlation with the amount of haemoperitoneum. Doctors should consider fluid resuscitation and urgent referral to gynaecologist for immediate operation even though the vital signs are normal, as patient may already have significant intraperitoneal bleeding.