Abstract: In this paper a method based on additive C-13 shift relationships, using empirical substituent chemical shift paremeters, is described. It is applicable to aliphatic saturated hydrocarbons earring 45 functional groups as well as the carbons contained in these functional groups. It can also take care of alicyclic compounds, although it's accuracy tends to be lower. The computer program is written in FORTRAN IV-plus and BASIC, and run on a VAX 11/780, or a PDF 11/23, or a microcomputer IBM PC/XT etc.