The incidence, the clinical characteristics, and the outcome of Kaposi sarcoma (KS) in patients after hematopoietic stem cell transplantation (HSCT) were assessed. During the period 1987-2018, 13 cases of KS were diagnosed, 3 females and 10 males, median age of 50 years, median time from HSCT of 7 months. KS had an incidence of 0.17% in allogeneic and 0.05% in autologous HSCT. HHV-8 was documented in eight of nine tumor tissue samples assessed. The organ involvement was: skin in nine, lymph nodes in six, oral cavity in four, and visceral in three patients, respectively; seven patients had >1 organ involved. Five patients had immunosuppression withdrawn, whereas four and three patients received radiotherapy and chemotherapy, respectively. Eight patients are alive (median follow-up 48 months, range 5-128), whereas five patients died after a median time of 8 months from the diagnosis of KS. However, no death was caused by KS. We conclude that the incidence of KS after HSCT is very low. Although KS can be managed with the reduction of immunosuppression, visceral forms may require chemotherapy and/or radiotherapy. The low prevalence of KS indicates that screening for HHV-8 serology and surveillance for HHV-8 viremia are not indicated in HSCT patients.