AIM: To investigate the clinical impact of post-hyperthermic intraperitoneal chemotherapy(HIPEC) leukopenia, intraperitoneal and combined intravenous/intraperitoneal drug administrations were compared.METHODS: Two patient cohorts were retrospectively analyzed regarding the incidence of postoperative leukopenia. The first cohort(n = 32) received Mitomycin C(MMC)-based HIPEC intraperitoneally(35 mg/m2 for 90 min) and the second cohort(n = 10) received a bidirectional therapy consisting of oxaliplatin(OX)(300 mg/m2 for 30 min) intraperitoneally and 5-fluorouracil(5-FU) 400 mg/m2 plus folinic acid 20 mg/m2 intravenously. The following data were collected retrospectively: Age, sex, length of operation, length of hospital stay, amount of resection including extent of peritonectomy, peritoneal cancer index, CC(completeness of cytoreduction)-status and leukocyte-count before cytoreductive surgery(CRS) and HIPEC, on days 3, 7 and 14 after CRS and HIPEC. HIPEC leukopenia was defined as < 4000 cells/m3. RESULTS: Leukopenia occurred statistically more often in the MMC than in the OX/5-FU-group(10/32 vs 0/10; P = 0.042). Leukopenia set-on was on day 7 after CRS and MMC-HIPEC and lasted for two to three days. Three patients(33%) required medical treatment. Patients affected by leukopenia were predominantly female(7/10 patients) and older than 50 years(8/10 patients). Thelength of hospital stay tended to be higher in the MMCgroup without reaching statistical significance(22.5± 11 vs 16.5 ± 3.5 d). Length of operation(08:54 ± 01:44 vs 09:48 ± 02:28 h) were comparable between patients with and without postoperative leukopenia. Prior history of systemic chemotherapy did not trigger postHIPEC leukopenia. Occurrence of leucopenia did not trigger surgical site infections, intraabdominal abscess formations, hospital-acquired pneumonia or anastomotic insufficiencies. CONCLUSION: Surgeons must be aware that there is a higher incidence of postoperative leukopenia in MMCbased HIPEC protocols primarily affecting females and older patients. AIM: To investigate the clinical impact of post-hyperthermic intraperitoneal chemotherapy (HIPEC) leukopenia, intraperitoneal and combined intravenous / intraperitoneal drug administrations were compared. METHODS: Two patient cohorts were retrospectively analyzed against the incidence of postoperative leukopenia. The first cohort (n = 32) received Mitomycin C (MMC) -based HIPEC intraperitoneally (35 mg / m2 for 90 min) and the second cohort (n = 10) received a bidirectional therapy consisting of oxaliplatin (OX) (300 mg / m2 for 30 min) and the 5-fluorouracil (5-FU) 400 mg / m2 plus folinic acid 20 mg / m2 intravenously. The following data were collected retrospectively: Age, sex, length of operation, length of hospital stay, amount of resection including extent of peritonectomy, peritoneal cancer index, CC (completeness of cytoreduction) -status and leukocyte-count before cytoreductive surgery (CRS) and HIPEC, on days 3, 7 and 14 after CRS and HIPEC. HIPEC leukopenia was defined as <4000 ce lls / m3. RESULTS: Leukopenia was more often in the MMC than in the OX / 5-FU-group (10/32 vs 0/10; P = 0.042) -HIPEC and lasted for two to three days. Three patients (33%) required medical treatment. Patients affected by leukopenia were predominantly female (7/10 patients) and older than 50 years (8/10 patients). Thelength of hospital stay tended (of 22.5 ± 11 vs 16.5 ± 3.5 days). Length of operation (08:54 ± 01:44 vs 09:48 ± 02:28 h) were comparable between patients with and without postoperative Prior history of systemic chemotherapy did not trigger postHIPEC leukopenia. Occurrence of leukemia did not trigger surgical site infections, intraabdominal abscess formations, hospital-acquired pneumonia or anastomotic insufficiencies. CONCLUSION: Surgeons must be aware that there is a higher incidence of postoperative leukopenia in MMCbased HIPEC proto colsover affecting females and older patients.