Mainly among children incidental ingestion of conventional lamp oils (paraffin oil) is responsible for casual intoxications with severe pulmonary toxicity and fatal consequences. On the basis of the isolated blood-free perfused rat lung we developed a model to study the acute toxic effects of lamp oil. Three oils were studied: conventional paraffin lamp oil (kinematic viscosity 1.62 10 - 6 m 2 /sec), the methyl ester Edenor(R) ME C12 70 (2.7 10 - 6 m 2 /s) and another ester Edenor(R) LPL (4.5 10 - 6 m 2 /s). The oils were instilled into the trachea of isolated rat lungs and the changes in lung mechanics (tidal volume, pulmonary compliance and pulmonary conductance) as well as edema formation (increase in lung weight) studied. Instillation of as little as 10 μl paraffin oil caused complete failure of lung functions within 20 min and even 2 μl caused noticeable edema. Similar results were obtained with Edenor(R) ME C12 70, which appeared to be even more toxic than paraffin oil, while Edenor(R) LPL was less toxic. We conclude that tracheal instillation of oils into isolated perfused rat lungs may be a useful model to study the toxicity of lamp oils in vitro. Our findings further suggest that Edenor(R) LPL may be a safer alternative for use as a lamp oil than paraffin oil.