For the purpose of studying the mechanism of tetramethylpyrazine (TMP) to prevent the restenosis after percutaneous transluminal coronary angioplasty (PTCA) and promote blood circulation to remove stasis. 40 micrograms of TMP was used to treat cultured vascular smooth muscle cells (VSMs). The total RNA was extracted from treated VSMC. The RNA Northern blot hybridization with procollagen genes alpha i-I and alpha 1-III probes was used to investigate its change in mRNA level. The results indicated that TMP could inhibit significantly the transcription of procollagen genes alpha 1-I and alpha 1-III.