Preclinical studies showed the Nitric Oxide (NO) gel significantly promoted hair follicle formation and growth in both rat and mouse models. The NO gel induced major physiological, developmental, and structural changes in the skin of mammals to increase the number of hair follicles, follicle stem cell development and regeneration as well as hair shaft elongation, and accelerated hair growth rate. Based on our animal model findings, the investigators hypothesize that the nitric oxide releasing gel could be used as a medical treatment for hair growth in humans. The objective of this trial is to evaluate the safety and efficacy of this NO gel (XN-001), in comparison with a placebo gel in subjects in a 24-week treatment schedule.

Inclusion Criteria:

1. Male subjects >= 20 and <= 65 years of age.
2. Subjects with hair loss caused by androgenetic alopecia.
3. Subjects who are healthy without any serious diseases that require hospitalization during the study period.
4. Subjects who are capable of understanding and having signed the Informed Consent Form after detailed description of the treatment procedures and potential risks and benefits.

Exclusion Criteria:

1. Subjects who received any treatment for hair loss within 6 months or finasteride within 12 months
2. Subjects with diagnosis of cancer and is still on active therapies.
3. Subjects with diagnosis of an active disease and is still under regular treatment for this disease
4. Subjects with hair loss caused by a known chronic disease.
5. Subjects who are on vasodilators or other medication with pharmacological actions that may lead to excessive formation of nitric oxide or may accentuate drug effects due to excessive formation of nitric oxide.
6. Subjects with thyroid disease.
7. Subjects iron-deficiency anemia.
8. Subjects with skin diseases of the scalp, including severe seborrhoeic dermatitis, psoriasis, lichenoid eruption, tinea capitis, or other scalp infections or infestations
9. Subjects with any known allergic reaction to any ingredient in the 2 gel preparations.
10. Subjects who have been enrolled into any clinical study in the preceding 6 months prior to randomization.
11. Subjects who have taken medications that are known to induce hypotrichosis or hypertrichosis.