Introduction High-grade serous primary peritoneal cancer is highly sensitive to platinum-based chemotherapy with response rates above 80%. Incidence of immediate hypersensitivity reactions to carboplatin is estimated to be between 15% and 20%, usually seen after a mean of 6–8 infusions, with patients developing moderate to severe reactions. Case report A 62-year-old female patient with stage IIIC primary high-grade serous carcinoma of the peritoneum was diagnosed and chemotherapy with carboplatin and Paclitaxel was indicated by the oncology service and patient shows response. At 6 months the patient returns, a new PET/CT reports progression of the disease. Carboplatin/paclitaxel cycles are restarted and in the eight cycle of carboplatin within 40 min of administration, she presented severe anaphylaxis with skin, pulmonary, cardiac and atypical symptoms. Infusion is suspended and intramuscular epinephrine with hydrocortisone and chlorphenamine are administered resolving symptoms. Management and outcome Intradermal skin test with carboplatin at the concentration of 10 mg / ml (dilution 1: 100) was positive. Due to the symptoms presented and to continue the safe reintroduction to carboplatin, a 4 bag 16-step drug desensitization protocol was carried out at a total dose of 620 mg with no hypersensitivity reactions. Discussion Prolonged carboplatin use is associated with an increased incidence of carboplatin-related hypersensitivity reactions. And in patients that present hypersensitivity reactions, a safe and effective carboplatin desensitization protocol can be carried out to reach the administration of a full dose. Desensitization protocol induces tolerance to a drug temporarily and is dependent on continuous exposure.