A data sample corresponding to almost two million hadronic Z decays collected by the ALEPH detector at LEP has been searched for monojet events. Three events were found, in agreement with the expectation from the process , with . Two events are hadronic, the third one being an e+e− pair. All monojet masses are in excess of 3 GeV/c2, and two of the event have large transverse momenta: 18.5 and 20.3 GeV/c. These kinematic characteristics are quite unlikely in the process . The probability of their occurence increases substantially when processes involving further Z or W exchanges are taken into account, but still remains at the 5% level.