Nanocomposites of polyamide 6 (PA6) with different concentrations of silane-treated, organic-treated, and nontreated nanoparticles of halloysite (HNT) and montmorillonite (MMT) had their microstructure and melt and solid state rheological behavior analyzed. The microstructure analysis was done using transmission electron microscopy (TEM) and wide angle X-ray diffraction (WAXD); the effectiveness of the silanization was studied by thermogravimetric analysis (TGA) and Fourier transform infrared. It was found that exfoliation occurred in the organic-treated MMT, but not in the silane-treated MMT and that silanization was small in the HNT nanoparticles (due to its low amount of surface hydroxyls groups). Steady state shear, small amplitude oscillatory, and transient tests also indicated that: (i) only the nanocomposites with organic-treated MMT, at concentrations above the theoretical percolation threshold developed a percolated network; (ii) the silane treatment increased the shear elastic modulus (G) of the PA6/HNT nanocomposites in the solid state, but not of the PA6/MMT; (iii) the organic-treated MMT formed composites with the highest G, as expected. Thus, it was concluded that the HNT nanoparticles had a high potential as nanofiller for PA6, but further research on more efficient compatibilizers for HNT is still needed. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers.