The combination of testosterone and dutasteride is intended for use in hypogonadal men. This study will evaluate the effect of 28-day repeat dosing of this combination with varying BID doses of testosterone (T), in combination with a fixed BID dose of dutasteride (D), as well as a testosterone alone arm, on T and D levels in the blood. The rationale is to look for the effects of each compound on the other, and to look for any safety problems that may result when the 2 drugs are given together.

Inclusion criteria:

• Have a diagnosis of primary or secondary hypogonadism.
• Have very low testosterone levels on 2 separate days.
• Have a BMI within range of 18.5-35kg/m2.
• Have not taken dutasteride for one year, or finasteride for the past 3 months.

Exclusion criteria:

• Have had or have breast or prostate cancer, malabsorption syndrome, sleep apnea, psychiatric illness, polycythemia, or any other clinically significant current condition.
• Are diabetic with an HbA1c >= 8.
• Are taking any androgens, such as testosterone, saw palmetto.
• Are taking ritonavir, indinavir, itraconazole, ketoconazole, erythromycin, warfarin, digoxin, cholestyramine, or any dietary/herbal/vitamin supplements.
• Would donate more than 500 ML of blood over a 2 month period.
• Physician does not think it is a good idea for you to participate in the trial. - Are unwilling to abstain from alcohol during the study.
• Have a positive urine drug screen test.
• Plan to change your smoking habits during the course of the trial.
• Have Hepatitis C, Hepatitis B, or HIV.
• Have a lab or EKG abnormality.
• High or low blood pressure.
• Have used of any investigational drug or device during the study or within 30 days prior to 1st dosing of study medication.