Idiopathic heavy menstrual bleeding (HMB; IHMB) is a common gynecological problem with no pelvic pathology or general bleeding disorder. Herbal remedies are commonly used to treat HMB. This systematic review aimed to assess the effectiveness and safety of herbal preparations for the treatment of IHMB. MEDLINE, Ovid, and the Cochrane Central Register of Controlled Trials were searched from inception to 23 August 2015. Only randomized controlled trials were considered. Three randomized controlled trials were included in this systematic review. Different herbal preparations were used in the included trials. In two studies, Ginger capsules and myrtle fruit syrup significantly reduced the menstrual duration and blood loss compared with placebo based on the pictorial blood loss assessment chart score (p < 0.001, p = 0.01). In another trial, Punica granatum flower capsules were as effective as tranexamic acid capsules in reducing the mean (SD) pictorial blood loss assessment chart score, with no significant difference between the two treatments (p = 0.3). The results show that the methods used in these trials may reduce menstrual bleeding in women with IHMB. Additional well-designed trials are needed to investigate the safety and efficacy of herbs for the treatment of women with IHMB or other forms of HMB.