Extensive burn wound coverage remains a major problem in acute and reconstructive stages due to shortage of autologous skin donor sites. Many reports have described successful coverage of extensive burn wounds by using cultured keratinocytes sheet graft alone or overlaying a glycosaminoglycan substrate, allodermis or xenodermis. In our experience, the use of Boyce and Ham's serum-free medium made the preparation of keratinocyte cultures simple and the cell growth was prompt. In this study, one of the supplements in Boyce's culture medium, the bovine pituitary extract (BPE at concentration of 140 micrograms/ml), was replaced by different concentrations of fresh frozen porcine pituitary extract (PPE). The protein concentration of the original preparation of PPE was also 140 micrograms/ml but in which 375 +/- 21 pg/ml (1/10 dilution) of platelet-derived growth factor (PDGF) was detected by immunoassay (PDGF ELISA). Our results proved that PPE is an ideal supplement for the in vitro growth of keratinocytes, and when its protein concentration is 350 micrograms/ml will induce a significant keratinocyte growth by day 9 when compared to the regular BPE and also to the other concentrations of PPE (P < 0.05).