1. Lipoprotein lipase activity and hormone-sensitive lipase activity were investigated in subcutaneous lipomas removed from two patients and compared with the enzyme activities in subcutaneous adipose tissue from two normal subjects.
2. Confirmation was obtained of the presence of lipoprotein lipase activity in lipomas with an activity fifteen to forty-five times that in the two control samples.
3. Hormone-sensitive lipase activity was demonstrated in lipomas under basal conditions of assay as well as in the presence of adrenaline plus theophylline. However, compared with the non-lipomatous fat samples, these activities were lower, as was the magnitude of the lipolytic response to adrenaline plus theophylline.
4. The significance of these measurements of enzyme activity and their role in the pathogenesis of lipomas are briefly discussed.