We have analyzed high resolution spectra of several slightly to moderately reddened stars collected at two observatories: ESO (La Silla) and Terskol (Northern Caucasia), to estimate the abundance of the C5 molecule in the interstellar medium. We confirm the presence of a feature near 4975 Å which appears to be a weak DIB rather than the predicted C5 band since the origin band near 5109 Å remains invisible even in spectra of high signal-to-noise ratio ( ~ 2500) and spectral resolution (R ~ 220 000). This confirms that the C5 abundance in translucent interstellar clouds is very low. We estimate its limit as low as 1011 cm-2 in the scale E(B-V)=0.35 for ``zeta" type objects that is two times lower than that of Maier et al. (2002). Based on data collected at the ESO 3.6 m telescope operated on La Silla Observatory, Chile and 2-m telescope of the Terskol Observatory, Russia.