  The results of a survey of 63 galactic star-forming regions in the 6_K-5_K
and 5_K-4_K methyl acetylene lines at 102 and 85 GHz, respectively, are
presented. Fourty-three sources were detected at 102 GHz, and twenty-five at 85
GHz. Emission was detected towards molecular clouds with kinetic temperatures
20-60 K (so-called ``warm clouds''). The CH3CCH abundances in these clouds
appeared to be about several units X 10^(-9). Five mapped sources were analyzed
using the maximum entropy method. The sizes of the mapped clouds fall within
the range between 0.1 and 1.7 pc, virial masses - between 90-6200 Msun, and
densities - between 6 X 10^4 and 6 X 10^5 cm^(-3). The CH3CCH sources spatially
coincide with the CO and CS sources. Chemical evolution simulations showed that
the typical methyl acetylene abundance in the observed clouds corresponds to an
age of ~ 6 X 10^4 years.
