Abstract: This invention relates to a valve system for reciprocating engines, said system comprising at least two cylindrical guides obtained in the cylinder head; a valve for each guide, said valve being slidable inside the guide itself, without never projecting into the cylinder; ducts or channels obtained in said cylinder head which make one of said guides and hence the cylinder itself to communicate, following to the motion of the corresponding valve, with the induction or the exhaust system; and sealing means between each one of said valves and the corresponding guide; said valves being designed so as to open in their motion the passage of the corresponding channel or duct towards the outside of the cylinder.