Photographic methods for hair evaluation are frequently proposed as an alternative to more invasive methods (trichogram or biopsy). The reliability in terms of quantitative follow-up of hair growth has not been evaluated properly. We report results of comparative studies of scalp hair evaluation with various photographic methods. Statistically significant findings were a better detection of scalp hairs using the original enlargement × 3 as compared to × 2 (212 vs. 167 hair follicles/cm²) and a more acceptable estimate of linear hair growth rate with ‘scalp immersion proxigraphy’ (SIP) (0.317 mm/day) as compared with classical phototrichogram pictures where this variable was underestimated by 30% on average (0.27 mm/day). SIP-generated linear hair growth rates were very close to the micrometric method (0.37 mm/day). Therefore SIP × 3 images appear preferable for hair growth monitoring during clinical trials.