Alveolar type II cells from adult rat lung have the enzymic capability to acylate 1-palmitoyl-lysophosphatidyl-glycerol, using palmitoyl-CoA to form dipalmitoylphosphatidylglycerol. 2. On a protein basis the acylation of 1-palmitoyl-lysophosphatidylglycerol is at least 2-fold more active in sonicated type II cells than in whole lung homogenates. 3. Both type II cells and whole lung homogenates show higher activity towards palmitoyl-CoA than towards oleoyl-CoA for acylation of 1-palmitoyl-lysophosphatidylglycerol. 4. Both in type II cells and in whole lung homogenates the rates of acylation of 1-palmitoyl-lysophosphatidylglycerol and 1-palmitoyl-lysophosphatidylcholine with palmitate are of the same order of magnitude, while the rate of acylation of 1-palmitoyl-lysophosphatidylethanolamine is much lower.