To describe and assess the interobserver reproducibility of a new method for evaluation of ovarian vascularization using spatiotemporal image correlation-high definition flow (STIC-HDF). Stored 4-dimensional (4D) STIC-HDF volume data from 39 healthy pre-menopausal fertile women (aged <35 years) examined in the follicular part of the menstrual cycle by transvaginal sonography were assessed by two different examiners blinded from each other (one in Spain the other in Poland). Using 1-cm(3) spherical sampling, the vascularization index (VI) from the most vascularized part of the ovarian stroma was calculated at two different moments of the cardiac cycle (systole and diastole). System settings were kept constant for all patients (pulse repetition frequency, 0.6 kHz; gain, 0.2) with a depth of 40 mm. Analysis was performed offline using 4D software on a personal computer. On the basis of VI and vascularization-flow index (VFI) values during systole and diastole, 4 new 4D indices were defined: 4D systolic/diastolic volumetric index (4D-SDVI = VI(syst)/VI(diast)), 4D hemodynamic volumetric index (4D-HVI = [VI(syst) + VI(diast)]/[VI(syst) - VI(diast)]), 4D systolic/diastolic vascularization-flow index (4D-SDVFI = VFI(syst)/VFI(diast)), and 4D hemodynamic vascularization-flow index (4D-HVFI = [VFI(syst) + VFI(diast)]/[VFI(syst)- VFI(diast)]). Reproducibility of measurements was estimated by calculating the intraclass correlation coefficient (ICC). The systolic VI, diastolic VI, 4D-SDVI, 4D-HVI, systolic VFI, diastolic VFI, and 4D-HVFI showed good reproducibility (ICC, 0.992, 0.994, 0.879, 0.915, 0.995, 0.995, and 0.893, respectively). The 4D-SDVFI showed moderate reproducibility (ICC, 0.797). We describe 4 new 4D vascular indices for assessing tissue vascularization using STIC-HDF technology. Assessment of ovarian vascularization using this STIC-HDF spherical sampling is reliable. The calculation of these new indices is reproducible between two different examiners.