Androgenetic alopecia (AGA) is a common yet poorly understood condition. In particular, the significance of inflammatory cells close to the infrainfundibulum of transitional hairs remains obscure. This study was conducted in 20 men who used a lotion containing the antimicrobials, piroctone olamine and triclosan, regularly for 18 months. At entry, mild pruritus and abnormal hair loss were reported by the volunteers. During treatment, pruritus resolved rapidly. Comparison of clinical photographs and trichograms taken at 3-month intervals suggested signs of hair regrowth with moderate increase in density of transitional hairs. Biopsies taken at 6-month intervals were processed for immunohistochemistry. There was a decrease in the density of activated T cells in the region of the follicular infrainfundibulum and isthmus over time. IgG deposits found within the epithelial sheaths at entry to the study were absent in the subsequent biopsies. The volume of the sebaceous glands, as assessed by computerized morphometry, was not modified by the treatment. It was concluded that inflammation associated with AGA transitional hairs may be driven by the presence of microorganisms harboured in the infrainfundibulum. They may modulate the severity of AGA and may potentially be controllable. This offers a new possibility of prevention and partial reversal of hair loss in AGA.