2-Amino-1,3-propanediol compounds of the formula (I) ##STR1## wherein R is an optionally substituted straight- or branched carbon chain, an optionally substituted aryl, an optionally substituted cycloalkyl or the like, and R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are the same or different and each is a hydrogen, an alkyl, an aralkyl, an acyl or an alkoxycarbonyl, pharmaceutically acceptable salts thereof and immunosuppressants comprising these compounds as active ingredients.The 2-amino-1,3-propanediol compounds of the present invention show immunosuppressive action and are useful for suppressing rejection in organ or bone marrow tranplantation, prevention and treatment of autoimmune diseases or as reagents for use in medicinal and pharmaceutical fields.