Chemical processes can unfold in surprising and unpredictable ways when performed in the presence of chaotic advection. But the underlying interplay between reaction and flow remains poorly understood, and the "design" rules needed to rationally apply these effects are largely unknown. Here, we show how this fundamental coupling can be harnessed in flow fields generated by microscale thermal convection to achieve rapid biochemical replication of DNA through the polymerase chain reaction (PCR)-a process that involves cyclically heating and cooling an aqueous reagent cocktail to temperatures corresponding to denaturation of the double-stranded (ds) template DNA (ca. 95 8C), annealing of primers at specific locations on the denatured single-stranded fragments (ca. 50-60 8C), and enzyme-catalyzed extension to synthesize the complementary strands (ca. 72 8C). Although the reactor configuration to execute convective PCR is conceptually simple (i.e., the classical Rayleigh-BØnard system in which a fluid is heated from below in a cylindrical chamber of height h and diameter d; Figure ), remarkably complex flow phenomena can emerge when convective turbulence occurs even though the flow is inertially laminar. [1] These states can be mapped in a parameter space governed by the aspect ratio (h/d) and the Rayleigh number (Ra = [gb-(T 2 ÀT 1 )h 3 ]/na; where b is the fluids thermal expansion coefficient, g is gravitational acceleration, T 1 and T 2 are the temperatures of the top (cool) and bottom (hot) surfaces, respectively, h is the height of the fluid layer, a is the thermal diffusivity, and n is the kinematic viscosity).