Formaldehyde is used in ruminant feeding for different purposes including the protection of dietary proteins from ruminai degradation. The formaldehyde content of milk of goats fed various levels of formaldehyde‐treated soybean oil‐meal has been determined by using a sensitive HPLC method. Results showed a significant linear correlation between ingested formaldehyde and formaldehyde concentration in milk. About 0.02% of ingested formaldehyde was excreted in milk, as free formaldehyde.