The induction of acyl-CoA-binding protein (ACBP) and ACBP mRNA was investigated in 3T3-L1 cells during growth and insulin-induced differentiation. The level of ACBP relative to both total soluble protein and DNA increased during insulin-stimulated conversion of 3T3-L1 cells from preadipocytes into fully developed adipocytes. So did the total rate of lipogenesis, as measured by incorporation of [1-14C]acetate. A similar increase in ACBP mRNA relative to total RNA was observed. These results therefore suggest that ACBP plays a specific role in the lipogenic process. However, this role might be indirect, as the increase in lipogenesis preceded the increase in ACBP. The significance of this finding is discussed.