The effects of lipolytic and antilipolytic agents on glucose transport and glycerol production in isolated human fat cells was investigated. Insulin and various adenylate cyclase inhibitors caused a dose-dependent stimulation of 3-O-methyl glucose transport. The maximum effects were 245 per cent and 100 per cent, respectively. The lipolytic agents isoprenaline, forskolin and dibutyryl cyclic AMP also caused dose-dependent stimulation of 3-O-methyl glucose transport, the maximum effect being about 100 per cent. Enprofylline counteracted the 3-O-methyl glucose transport-stimulating effect of both the lipolytic and antilipolytic agents but altered only the effect of antilipolytic agents on glycerol production. Enprofylline alone had no effect on 3-O-methyl glucose transport activity but stimulated glycerol production. It is on 3-O-methyl glucose transport activity but stimulated glycerol production. It is concluded that stimulation as well as inhibition of lipolysis at different steps in the lipolytic system is associated with acceleration of glucose transport in human fat cell which does not seem dependent upon the lipolysis rate.