The manual procedure of drafting engineering designs is fast becoming obsolete. Newer systems for computer-aided design (CAD) drafting are emerging everyday. However, the process of including tolerance details in these CAD drawings is extremely complex and has very little evidence of existence in past literature. This paper identifies and computerizes a procedure for automatic tolerance assignment in CAD drawings. The procedure developed envelopes three major stages: feature extraction, feature infcrcncing, and rule-based tolerance allocation. The system was implemented on an IBM-PC compatible. The results established through example analysis verify the utility of the system.