Subjects will be randomized to receive generic efavirenz 600 (Test formulation) or Stocrin(R) 600 tablets (Reference formulation)on study day 1 (period 1), then they will undergo a 24 hour intensive pharmacokinetic evaluation after ingesting a single dose of either the Test or Reference formulation. Additional pharmacokinetic samples 36, 48, 72, 120 and 192 hours postdose will be drawn.