Effect of Letrozole on Seminal Parameters in Men With Non Obstructive Azoospermia and Severe Oligozoospermia.

The investigators hope to learn if Letrozole is effective and safe in improving severe male infertility by increasing testosterone, decreasing oestradiol and stimulating sperm production thereby improving sperm motility (movement) and concentration. The study is being conducted because Letrozole is not yet proven to be a standard treatment in subjects with absent or very low sperm counts. The investigators are hoping to determine whether Letrozole is equal or superior to no treatment.