The present article considers the coil-to-globule transition behavior of atactic and syndiotactic poly(methyl methacrylates), (PMMA) in their theta solvent, n-butyl chloride (nBuCl). Changes in Rh in these polymers with temperature in dilute theta solutions were investigated by dynamic light scattering. The hydrodynamic size of atactic PMMA (a-PMMA-1) in nBuCl (M-w: 2.55 x 10(6) g/mol) decreases to 61% of that in the unperturbed state at 13.0 degrees C. Atactic PMMA (a-PMMA-2) with higher molecular weight (M-w: 3.3 x 10(6) g/mol) shows higher contraction in the same theta solvent (alpha(eta) = R-h(T)IRh (theta) = 0.44) at a lower temperature, 7.25 degrees C. Although syndiotactic PMMA (s-PMMA) has lower molecular weight than that of atactic samples (M-w: 1.2 x 10(6)), a comparable chain collapse was observed (alpha(eta) = 0.63) at 9.0 degrees C.