A detailed K-Ar and paleomagnetic study was made on the oldest outcropping lavas of the Roccamonfina volcano. The very first episodes of volcanism were concentrated at around 1 M.Y., whereas most of the activity occurred between 0.4 and 0.5 M.Y. After the formation of a caldera a second cycle of volcanism started at 0.25 M.Y. The paleomagnetic measurements indicate an episode of normal polarity at 1.10 + 0.05 M.Yr. The occurrence of this episode was suggested by Watkins (14) in 1968. There is no evidence of other magnetic events on younger rocks.