Line shift coefficients, line broadening coefficients, and line narrowing coefficients have been measured in the nu (1) + 3 nu (3) band of acetylene using a diode laser system operating at 788 nm and a multipass Herriot absorption cell. Experimental data have been obtained for 20 lines of the P and R branches broadened by N-2, O-2, air, and the rare gases He, Ne, Ar, Kr, and Xe. The observed line shapes could successfully be reproduced by employing Galatry and Rautian functions which include the phenomenon of Dicke narrowing. Our results for the line broadening coefficients are in good agreement with the values reported previously for other vibrational bands. Thus, the present work confirms the vibrational independence of the broadening coefficients. On the other side, we observed a clear dependence of the narrowing coefficients on rotation in a vibrational transition of acetylene for the first time. In addition, the line center frequencies have been determined with improved accuracy. (C) 2001 American Institute of Physics.