SummaryThe nature of the hyperlipemia in two 3‐week‐old male kittens, one of which was presented with the owner's complaints of retarded growth and white streaks on its eyes, was studied. Hypertriglyceridemia, hyper‐cholesterolemia, and reduced Post‐Heparin Plasma Lipolytic Activities (PHPLA) were observed in both animals. One of the kittens, however, was more severely affected and in addition, had lipemia retinalis and a marked lactescent, hyperchylomicronemic serum in spite of a short‐term fast before sampling. These findings are strikingly similar to those found in human Type I hyperlipoproteinemia due to familial Lipoprotein Lipase (LPL) deficiency. Diagnosis of persistent hyperlipemic syndromes in kittens should include the possibility of LPL deficiency as determined by PHPLA mea