Conjugated linoleic acid (CLA), a naturally occurring anticarcinogen found in dairy products, has received increasing attention in recent years. Twelve lactating Murrah river buffaloes (Bubalus bubalis) were used to study the profile of long-chain fatty acids in milk fat. Buffaloes were fed with natural pasture ad libitum. Milk samples were collected in the morning. Animals were grouped according to lactation stage (3-4 months). The composition of milk samples and fatty acid profile were analysed. Milk samples were refrigerated, homogenized and pasteurized to evaluate any possible effect of treatment on cis9, trans 11 octadecadienoic acid (CLA) level. Results showed that 59% of the long chain fatty acids were saturated. C16:0 was the most abundant fatty acid in buffalo milk, while C18:1 was the major unsaturated fatty acid. CLA level in buffalo milk was 4.83 mg/g of fatty acid methyl ester (FAME). There was a positive correlation between CLA and trans-11 C18:1 vaccenic acid. Any treatment of buffalo raw milk significantly modified CLA content or other fatty acids. Milk fat content of trans 11 C18:1 and CLA were closely related (r=0.90). A high quality of buffalo milk was obtained after a diet of only natural pasture in Northwest Argentina.