Few studies of in vivo normal human dermis characterization have been reported. In this study, the regularized spectral-log difference (RSLD) method was used for the estimation of the attenuation coefficient slope (ACS) in the forearm and thigh dermis with the objective of complementing previous studies on characterization of the forearm dermis and exploring the variations of ACS at different anatomic sites. Ten volunteers without skin injuries between 19-27 years old were scanned in the middle of the ventral side of the forearm and the anterior side of the thigh. The acquisition was performed using a high-frequency ultrasound scanner. The ACS was estimated within an analysis band spanning from 8 to 27 MHz. The average ACS in the forearm dermis was 2.07 dB. cm -1 . MHz -1 , which is in agreement with the slope found in the literature. In addition, a significant difference (p < 0.05) was found between the ACS in the forearm dermis and the thigh dermis (average ACS of 2.54 dB. cm -1 . MHz -1 ), which is consistent with the expected reduced collagen content in the forearm dermis compared with the thigh dermis due to increased sun exposure. Therefore, these results suggest that ACS has the potential to be used as a tool for in vivo skin characterization.