The stable gastric pentadecapeptide BPC 157 (GEPPPGKPADDAGLV; mol. wt. 1419), which is at present in phase II clinical trials for the treatment of inflammatory bowel disease, has been shown to counteract healing impairment by systemic corticosteroids in burned mice, both in vivo and in vitro, in the absence of carrier or protease inhibitor. Because of the particular healing problems associated with laser use, we have now studied the effect of pentadecapeptide BPC 157 on CO(2) laser injuries (Sharplan 1075 laser: 20 W, distance 12.5 cm, spot size 0.8 mm and exposure time 1s) created on the dorsal skin of anaesthetised male NMRI-Hannover mice. The injury was either not treated or treated by topical application of a thin layer of neutral cream containing pentadecapeptide BPC 157 (1 microg, 1 ng or 1 pg (dissolved in saline)/g) or vehicle only, once daily, with the first application 60 min after injury and the last 24 h before killing (1, 7 and 21 days after the laser application). BPC 157 consistently improved healing after the CO(2) laser injury, both macroscopically and microscopically. The effect was produced with a simple method of application and favourable peptide stability (no carrier), and confirms the effectiveness of an ointment containing 1 microg BPC 157 (dissolved in saline)/g neutral cream.