The effect of intramolecular crosslinking (IC) (cyclization) on gelation was studied using Monte Carlo simulations. The consumption of crosslinker in the IC process is proposed as one of the main reasons of significant overestimation of the gel point by Flory-Stockmayer theory. The system under study is atom transfer radical polymerization (ATRP) of a monomer and bifunctional (e.g. divinyl) crosslinker. The simulation method is based on dynamic lattice liquid algorithm (DLL) and reproduces changes of the system dynamics during polymerization. The effect of cyclization on gel point for various reagents ratios and dilutions was investigated. It is shown that intramolecular crosslinking does not change significantly the gel point in condensed systems (no solvent or below 10%). By contrast, it significantly increases gel points in diluted systems (40-90% of the solvent). (C) 2015 Elsevier Ltd. All rights reserved.