The short‐term inhalation toxicity of a medium‐boiling coal liquefaction product (CLP) was investigated in the rat. Groups of 5 male and 5 female Sprague‐Dawley rats were exposed to CLP aerosols at 25 mg/m3(low dose) or 100 mg/m3(high dose) 6 h/d, 5 d/w, for 4 wk. The control group was exposed to filtered air while the positive control received diesel fuel aerosols at 100 mg/m3. Male rats exposed to high‐dose CLP aerosols exhibited growth depression and increased hepatic aminopyrine de‐methylase activity compared to control animals. High‐dose females had decreased hemoglobin content and hematocrit values. These biochemical and hematological effects were not observed in animals of either sex treated with the diesel fuel. No other biochemical and hematological changes were observed. Mild histological changes occurred in the liver and thyroid of rats treated with CLP and diesel fuel aerosols. Based on the data presented, inhalation of CLP aerosols resulted in toxicological effects that were similar to those caused by dermal exposure.