OBJECTIVE Can a two-dose methotrexate treatment protocol improve the treatment success rate compared with a single-dose protocol in women with an ectopic pregnancy? CONCLUSIONS The two-dose protocol was not superior to the single-dose protocol for the treatment of ectopic pregnancy. BACKGROUND Although the two-dose methotrexate protocol for ectopic pregnancy was recently introduced to combine the efficacy and convenience of the fixed multi-dose and single-dose protocols, studies comparing the success rates, treatment satisfaction and acceptability of the single-dose and two-dose treatment protocols for ectopic pregnancy are currently lacking. METHODS A randomized trial was conducted on 92 participants with tubal ectopic pregnancy, between May 2013 and April 2015. METHODS Patients who were diagnosed with tubal ectopic pregnancy and who elected to undergo systemic methotrexate treatment were randomly assigned to follow either the single-dose (n = 46) or two-dose protocol (n = 46). The primary outcome measure was treatment success without surgical intervention. The secondary outcome measures were the incidence of methotrexate-associated side effects, β-human chorionic gonadotrophin (β-hCG) resolution time, cost of care received and treatment satisfaction. RESULTS There were no differences in baseline characteristics between the groups. The success rates between the single-dose and two-dose groups did not show a significant difference [82.6 versus 87.0%; relative risk (RR) 0.95; 95% confidence interval (CI) 0.80-1.13]. However, the success rate in a subgroup of participants with a pretreatment β-hCG level of >5000 mIU/ml appeared to be higher in the two-dose group than in the single-dose group (80.0 versus 58.8%), although the difference was not statistically significant. No significant differences in methotrexate-associated side effects, cost or treatment satisfaction were observed between the groups. The two-dose group required a lower number of days for the β-hCG level to decrease to <5 mIU/ml than the single-dose group (25.7 ± 13.6 versus 31.9 ± 14.1 days; P = 0.025). CONCLUSIONS Some caution is warranted in interpreting the results due to an overoptimistic sample size calculation on the basis of the biggest difference as reported in literature between the success rates of two protocols. CONCLUSIONS The single-dose protocol with the option to elaborate to a second dose in the case of treatment failure could stand as the treatment for most cases of ectopic pregnancy. BACKGROUND None. BACKGROUND www.clinicaltrials.gov, no. NCT01855568. 10 May 2013. 26 May 2013.