22 puppies with kaolin-induced hydrocephalus were repeatedly studied for 4 months in respect to their head size, ventricular size, pressure and cerebrospinal fluid (CSF) dynamics. The intraventricular pressure was markedly elevated during the first week and dropped towards the end of the first month of the hydrocephalic process. It then escalated and again returned to normal values after 3–4 months. Formation of CSF increased with age until it reached adult values of 0.049 ml/min at the age of 3 months. Absorption rates were very low initially. The absorptive capacity surpassed formation in the puppies which survived to the fourth month of the process. Ventricular size and rate of head enlargement correlated inversely with thickness of the skull. In the surviving puppies (4 out of 22) the hydrocephalic process seemed to have arrested.