The primary objective of this study is to determine the average bioequivalence of a generic efavirenz 600 mg tablet (test formulation)compared with Stocrin(R) 600 mg tablets (Reference formulation).The study is designed as an open label, randomized, crossover, 2-treatments, 2-period, 2-sequence, single dose pharmacokinetic study conducted in healthy volunteers. Subjects will be randomized to receive generic efavirenz 600 (Test formulation) or Stocrin(R) 600 tablets (Reference formulation)on study day 1 (period 1). Subjects will undergo a 24 hour intensive pharmacokinetic evaluation after ingesting a single dose of either the Test or Reference formulation. Subjects will provide additional pharmacokinetic samples 36, 48, 72, 120 and 192 hours postdose, respectively. Subjects will complete a wash out period from day 8 to day 28 during wich no study drug will be ingested. On day 29 subjects will ingest either the Test or the Reference formulation (opposite to the formulation received on period 1). All subjects undergo another 24 hour intensive pharmacokinetic evaluation and pharmacokinetics samples on days 36, 48, 72, 120, 192 pos dose, respectively. Adverse events and and concomitant medication will be documented throughout the study.