There is a need for a simple and reliable tool to evaluate hair loss and treatment effects in patients suffering from alopecia. In 2001 TrichoScan was introduced as a fully-automated method for the measurement of biological parameters of hair growth such as density, diameter and growth rate. However, the conventional phototrichogram method with manual marking of hairs on images is still performed and, although no real independent side-by-side comparison is available, the manual method is sometimes defined as the most precise method of measurement. The aim of this study was validation of the Trichoscan method by comparative assessment of TrichoScan analysis and manual marking of hairs. Digital images were taken from 10 patients with androgenetic alopecia (AGA) and validity and reliability of both methods were assessed. This study showed an excellent correlation of TrichoScan and manual marking of hairs. Considerable variability was noted in the results from manually evaluated images (range 2.71%-12.95%), compared to none in TrichoScan analyzed images. Results with TrichoScan were obtained more quickly and were more reproducible with a smaller margin of operator error. The consistency in the Trichoscan data allows statistically significant results to be obtained with a smaller sample size.