Acupuncture has been suggested as therapy for hot flashes in women with breast cancer and men with prostate cancer. In this systematic review, we sought to evaluate the long-term effects on vasomotor symptoms after the end of a defined treatment period of acupuncture in women with breast cancer and men with prostate cancer. Methods A literature search revealed 222 articles within the field. With defined exclusion criteria, we identified 17 studies. We also used the Jadad quality score and identified seven studies with a score of at least 3. Results Six of seven identified studies qualified for inclusion in an analysis that measured frequency of hot flashes weighted in relation to number of patients (n=172). The average reduction from baseline to end of acupuncture (ranging between 5 and 12 weeks of treatment) showed 43.2 % reduction of hot flashes. At the last follow-up (mean 5.8 months, range 3– 9 months) after the end of therapy, the weighted reduction from baseline was sustained at 45.6 % in the 153 of 172 patients (89 %) who were followed up. Conclusions Data from six prospective analyzed studies indicate at least 3-month effects after the end of acupuncture treatment for flashes in women with breast cancer and men with prostate cancer. However, larger randomized trials with long-term follow-up will be needed to confirm these preliminary findings.