A novel formulation of oral testosterone (T) undecanoate (TU) was evaluated in a phase 3 clinical trial.Determine efficacy, short-term safety, and alignment of new oral TU formulation with current U. S. approval standards for T replacement therapy.Randomized, active-controlled, open-label study.Academic and private clinical practice sites; enrolled patients were clinically hypogonadal men 18-65 years old.Patients were randomized 3:1 to oral TU, BID (JATENZO®; n=166) or a topical T product QD (Axiron®; n=56) for 3-4 mos. Dose titration was based on average T levels (Cavg) calculated from serial pharmacokinetic (PK) samples. T was assayed by LC-MS/MS. Patients had two dose adjustment opportunities prior to final PK visit. Safety was assessed by standard clinical measures, including ambulatory BP.87% of patients in both groups achieved mean T Cavg in the eugonadal range. NaF-EDTA plasma T Cavg for oral TU group was 403 ± 128 ng/dL (~14 ± 4 nmol/L; mean ± SD) [serum T equivalent ~ 489 ± 155 ng/dL (17 ± 5 nmol/L)] and for topical T was 391 ± 140 ng/dL (~14 ± 5 nmol/L). Modeling/simulation of T PK data demonstrated that dose-titration based on a single blood sample 4-6 hrs. after oral TU dose yielded efficacy (93%) equivalent to Cavg-based titration (87%). Safety profiles were similar in both groups, but oral TU was associated with a mean increase in systolic BP of 3-5 mm Hg.A new oral TU formulation effectively restored T to mid-eugonadal levels in hypogonadal patients.