The reported efficacy of various treatments for alopecia is difficult to compare based on a general lack of consideration in case reports/series and clinical trials of the spontaneous regrowth or baseline prognostic factors seen in alopecia areata and a general lack of quantification of hair growth. This report will give both the investigator and clinician guidelines for clinical trial design that will take into account variables known to effect efficacy results such as baseline severity, pattern, and duration of hair loss, age of the subject, and concomitant conditions that may impact on potential regrowth. Reliable methods of assessment of efficacy and response criteria that will enable direct comparison of results between agents will also be discussed.