Conclusions. Our measurements show that by and large, the S abundances in Galactic clusters trace reliably those in field stars. The only possible exception is Trumpler S. for which the SETE sulphur abundance implies an [S/Fe] ratio lower by roughly 0,4 dex than observed in field stars of comparable inetallicity, even though its LTE sulphur abundance is in line with abundances of field stars, Moreover the LIE sulphur abundance is consistent only with the abundance of another alpha-element Mg, in the same star, while the low NLTE value is consistent with Si and Ca. We believe that further investigation of departures from LIE is necessary, as well as observation of other Si lines in this star and in other stars of the same cluster, before one can conclude that the sulphur abundance in Trumpler 5 is indeed 0.4 dex lower than in field stars of comparable metallicity. The S abundances in our sample of stars in clusters imply that the clusters are chemically homogeneous for S within 0.05 dex.