The invention relates to novel secomacrolides from the class of erythromycin A, potential intermediates for preparation of novel macrolide antibiotics general formula ##STR1## and its pharmaceuticaly acceptable addition salts with inorganic or organic acids, wherein R.sub.1 represents hydrogen, C.sub.1 -C.sub.4 alkanoyl group, arylcarbonyl group and together with R.sub.2 and carbon atoms to which they are bound, cyclic carbonyl or thiocarbonyl group, R.sub.2 represents hydrogen or together with R.sub.1 and carbon atoms to which they are bound, cyclic carbonyl or thiocarbonyl group, R.sub.3 represents hydrogen, C.sub.1 -C.sub.4 alkanoyl or arylcarbonyl group,Z is hydrogen or L-cladinosyl group represented by formula (i) ##STR2## wherein R.sub.4 represents hydrogen or C.sub.1 -C.sub.4 alkanoyl group, W is hydrogen or D-desosaminyl group represented by formula (ii) ##STR3## wherein R.sub.5 represents hydrogen or C.sub.1 -C.sub.4 alkanoyl or arylcarbonyl group,X and Y together represent a lactone, or X is CH.sub.2 OR.sub.6, wherein R.sub.6 represents hydrogen or C.sub.1 -C.sub.4 alkanoyl group and Y is hydroxyl group.