This chapter examines the principles and clinical applications of ultrasound in female reproductive diagnostics, focusing on its technological foundations and common modalities. Ultrasound imaging relies on interactions between high-frequency sound waves and tissues—including reflection, refraction, and scattering—to generate real-time anatomical data. This chapter emphasizes the utility of transabdominal, transvaginal, and specialized interventional probes for procedures such as embryo transfer, ovarian follicle monitoring, and uterine pathology assessment. Central to this discussion is the role of two-dimensional (2D) grayscale ultrasound as the cornerstone modality, providing structural visualization through variations in echo intensity. Doppler ultrasound is introduced as a complementary tool for evaluating vascular dynamics, such as uterine artery perfusion and endometrial blood flow. Three-dimensional (3D) imaging is highlighted for overcoming spatial limitations of 2D scans, particularly in diagnosing uterine anomalies (e.g., septate uterus), polycystic ovarian syndrome, and endometrial receptivity. This chapter further explores contrast-enhanced ultrasound, which employs microbubble agents to noninvasively assess tubal patency via hysterosalpingo-contrast sonography (HyCoSy). By integrating advances in real-time imaging, computerized analysis, and multimodal systems, this chapter underscores ultrasound’s evolving role as a safe, noninvasive, and versatile tool. Clinical correlations—spanning infertility evaluation, early pregnancy monitoring, and gynecologic pathology—are systematically addressed to bridge theory with practice.