The paper discusses the topological Hall effect in the A-phase of MnSi, a transition metal compound. Recent small-angle neutron scattering (SANS) data suggests that the spin structure in the A-phase is a triple-Q state, or a superposition of three helices under 120 degrees, which is interpreted as a lattice of skyrmions—topologically stable knots in the spin structure. The authors report a distinct additional contribution to the Hall effect in the temperature and magnetic field range of the proposed skyrmion lattice, which is not observed or expected for a normal helical state. This contribution is quantitatively consistent with the skyrmion density derived from SANS and theory, providing clear experimental evidence that the magnetic structure observed in neutron scattering is indeed a skyrmion lattice. The topological Hall effect arises from a Berry phase collected by conduction electrons following the spin polarization of topologically stable knots in the spin structure. The measured Hall resistivity $\Delta \rho_{xy}$ in the A-phase is found to be $\approx 4.5 \pm 1 \, \text{n}\Omega\text{cm}$, which is in good agreement with the theoretically predicted value based on the skyrmion density and polarization. This study thus identifies the A-phase of MnSi as a lattice of skyrmions and provides direct observation of a topologically quantized Berry phase.The paper discusses the topological Hall effect in the A-phase of MnSi, a transition metal compound. Recent small-angle neutron scattering (SANS) data suggests that the spin structure in the A-phase is a triple-Q state, or a superposition of three helices under 120 degrees, which is interpreted as a lattice of skyrmions—topologically stable knots in the spin structure. The authors report a distinct additional contribution to the Hall effect in the temperature and magnetic field range of the proposed skyrmion lattice, which is not observed or expected for a normal helical state. This contribution is quantitatively consistent with the skyrmion density derived from SANS and theory, providing clear experimental evidence that the magnetic structure observed in neutron scattering is indeed a skyrmion lattice. The topological Hall effect arises from a Berry phase collected by conduction electrons following the spin polarization of topologically stable knots in the spin structure. The measured Hall resistivity $\Delta \rho_{xy}$ in the A-phase is found to be $\approx 4.5 \pm 1 \, \text{n}\Omega\text{cm}$, which is in good agreement with the theoretically predicted value based on the skyrmion density and polarization. This study thus identifies the A-phase of MnSi as a lattice of skyrmions and provides direct observation of a topologically quantized Berry phase.