Electronic Journal of Differential Equations, Vol. 2009(2009), No. 121, pp. 1-6. Title: Two component regularity for the Navier-Stokes equations Authors: Jishan Fan (Nanjing Normal Univ., China) Hongjun Gao (Nanjing Normal Univ., China) Abstract: We consider the regularity of weak solutions to the Navier-Stokes equations in $\mathbb{R}^3$. Let $u:=(u_1,u_2,u_3)$ be a weak solution and $\widetilde{u}:=(u_1,u_2,0)$. We prove that $u$ is strong solution if $\nabla\widetilde{u}$ satisfy Serrin's type criterion. Submitted August 28, 2009. Published September 29, 2009. Math Subject Classifications: 35Q30, 35K15, 76D03. Key Words: Navier-Stokes equations; regularity criterion; two component; multiplier spaces; Besov spaces.