Abstract. The resistivity, temperature, and magnetic field dependence of the anomalous Hall effect in a series of metallic Ga 1-x Mn x As thin films with 0.015≤ x ≤0.08 is presented. A quadratic dependence of the anomalous Hall resistance on the resistivity is observed, with a magnitude which is in agreement with Berry phase theories of the anomalous Hall effect in dilute magnetic semiconductors.In III-V dilute magnetic semiconductors such as Ga 1-x Mn x As, the ferromagnetic interaction between localised spins is mediated by the itinerant valence band electrons [1]. The participation of the free carriers in the magnetism results in a large anomalous Hall effect (AHE). The total Hall resistance is given byThe normal Hall term ρ NH and the anomalous Hall term ρ AH are proportional to the perpendicular components of the external magnetic field, B z , and the magnetisation, M z , respectively. The measured Hall resistance therefore contains information on both the magnetism and the carrier concentration p. However, separate extraction of this information is complicated by the field dependence of the resistivity ρ and the anomalous Hall coefficient R A (ρ), so that obtaining accurate values for the hole density in Ga 1-x Mn x As requires high magnetic fields and highly metallic samples [1,2]. A better understanding of the factors affecting the AHE is therefore desirable. The AHE is usually ascribed to a scattering anisotropy induced by the spin-orbit interaction [3]. Skew and side-jump descriptions give R A α ρ and R A α ρ 2 respectively, where ρ is the longitudinal resistance. The skew scattering picture is usually assumed in Ga 1-x Mn x As [1], although a quadratic dependence on ρ has been observed for In 0.88 Mn 0.12 As [4]. It was recently proposed that the AHE in the III-V ferromagnetic semiconductors is dominated by a disorder independent contribution which is due to a Berry phase acquired by the itinerant electrons, and results in a fieldindependent anomalous Hall conductivity [5]. In the following, we present measurements of the anomalous Hall effect in a series of metallic Ga 1-x Mn x As samples as a function of magnetic field and temperature, and compare our results to the predictions of reference [5]. 45nm thick Ga 1-x Mn x As films with 0.015≤ x ≤0.08 were grown on GaAs(001) by low temperature molecular beam epitaxy. The Mn concentration was controlled by varying the calibrated Mn/Ga ratio, and confirmed by x-ray fluorescence and xray diffraction measurements. Full details of the growth and structural characterisation are presented elsewhere [6]. In agreement with previous studies, a significant increase in T C was obtained by annealing at low temperatures (≈180ºC in the present case). This procedure resulted in a T C of up to 132K for x=0.06, as well as a reduction in the resistivity and magnetoresistance. Across the whole range of Mn doping studied, the samples are in the so-called 'metallic' regime, with conductivities in the range (200-700)Ω -1 cm -1 at low temperatures [2]. Magnetoresistance and Hal...