Abstract The performance of coded modulation scheme based on the application of integer codes to triangular quadrature amplitude modulation (TQAM) with 22m points constellation is investigated. A method of calculating the exact value of symbol error rate over AWGN channel in the case of TQAM combined with encoding by integer codes is described. Computation of error probability in the coded case is much more difficult because of more complex forms and in a sense uncertainties of decision regions. It is demonstrated that in the coded case computer simulation is a very good alternative. The results of simulations (symbol and bit error probabilities) in the case of coded 16, 64, and 256-TQAM simulations are graphically presented.