Objective To evaluate the safety and efficacy of foam sclerotherapy for bleeding internal hemorrhoids. Methods Consecutive adult patients (aged 18-60 years) with bleeding hemorrhoids were prospectively enrolled between March 2017 and March 2018. All patients were randomly assigned to the foam sclerotherapy (FS) group and the liquid sclerotherapy (LS) group. The foam and liquid sclerotherapy of hemorrhoids nucleus was performed by cap-assisted colonic endoscopy. Results A total of 108 patients were enrolled, including 62 males (57.4%) with mean age of 44.0±7.6 years. There was no significant difference in gender, age, or body mass index between the FS (n = 55) group and the LS (n =53) group. The total amount of lauromacrogol injection in the FS group was 3.7±0.9 mL, which was significantly lower than that in the LS group (8.0±2.2 mL, P<0.001）. In the LS group, 8 patients (15.1%) developed bleeding after needle removal, which was significantly higher than that in the FS group [5.5%(3/53), P=0.022]. Significant pain was found in 2 patients (3.8%) in the LS group and 0 in the FS group (P= 0.025). The short-term cure rate and effective rate of the FS group were 87.3% (48/55) and 9.1% (5/55), while those were 69.8% (37/53) and 22.6% (12/53) in the LS group, respectively (P=0.046). Conclusion Foam sclerotherapy is safe and effective in the treatment of bleeding internal hemorrhoids.