RIS Metropolis Monte Carlo (RMMC) simulations were used to determine the unperturbed theta-state chain dimensions of atactic stereoconfigurations of poly (2-ethylbutyl methacrylate) [PEBMA]. Root mean-squared end-to-end distance (←r 2→ o/M) 1/2 and characteristic ratio (C n) were calculated along with the backbone torsion angle distribution. The simulated properties are in very good agreement with experimental results. The values of the PEBMA chain dimensions are in-between those corresponding ones for poly(n-butyl methacrylate) and poly (n-hexyl methacrylate) thereby showing the effect of branching in the side-chain. Copyright © 2012 Wiley Periodicals, Inc.