Positron emission tomography records radiation emitted during the annihilation of positrons. This method is applied in neurology, cardiology, oncology and for locating inflammation foci; it also has an important role in gynecology. The paper presents the application of positron emission tomography for the diagnosis of ovarian and breast cancer and in cervical cancer. Breast cancer is the most common cancer among women. Endometrial, ovarian and cervical carcinoma are the fourth, fifth and sixth most prevalent cancers, respectively. These diseases are the second (breast cancer), fourth (ovarian cancer), seventh (cervical cancer) and tenth (endometrial cancer) cause of death due to cancer among women. Positron emission tomography combined with computed tomography (PET/CT) using ¹⁸F-fluorodeoxyglucose, which is increasingly widely available, allows for disease staging during one scan. In the case of breast cancer PET/CT with ¹⁸F-fluorodeoxyglucose is characterized by high sensitivity mainly in triple-negative cancer and in inflammatory cancer. Other forms of breast cancer are characterized by lower glucose metabolism and can give false-negative results. PET/CT ensures higher accuracy in the diagnosis of recurrent breast cancer than other imaging methods. PET/CT is also of high utility for the staging of cervical cancer and detection of its recurrence and, in particular, for radiotherapy planning. The procedure is highly sensitive in the detection of metastatic lymph nodes both in cervical and endometrial cancer. This method is very effective in the assessment of ovarian cancer recurrence with increased tumor marker levels. PET/CT scan results affect therapeutic decisions in a substantial proportion of patients with ovarian cancer.