I. A model of chronic ethanol administration has been used to study the effects of chronic ethanol consumption on the general metabolism of lactating rats on day 15 after delivery. 2. We have studied the effects of ethanol on calorics, food and fluid intake. body weight, circulating parameters such as glucose, glycerol, free fatty acids (FFA). triacylglyccrots (TAG), amino ncids (AA), ketone bodies, insulin and ethanol levels and liver composition. 3. Chronic ethanol consumption markedly incrr.ascs the levels of circulating D-OH-butyrate (B-OB-B), glycerol and FFA, while those of acetoacetate (AcAc), glucose, insulin and TAG remain constant. With the only exception of an increase in Glu + Gin levels, plasma AA dccre;1se in the alcohol-treated rats, the change being significant for Ala, Pro, Lys, Alg, Val, Phe and 4-OH-poline. 4. In the liver ethanol treatment causes an increment in TAG concentration and a decrease in glycogen content. 5. In conclusion, chronic ethanol consumption produces notable alterations in the metabolism of lactating rats, which may diminish the efficiency (1f lactation, influencir g milk production and, therefore, the pups' development.