Research with schizophrenic out-patients has shown that antipsychotic medication reduces relapse rates. This protective factor may operate partially by raising the threshold for relapse in the face of environmental stressors such as life events and high levels of familial expressed emotion. A prospective, longitudinal design was employed in the monthly collection of life-events data with 23 recent-onset schizophrenic out-patients. In a between-subjects ANOVA, a significantly higher frequency of independent life events was found in the month prior to a relapse for ten patients on medication, as compared with the analogous month for 13 drug-free patients. These findings suggest that neuroleptic medication may produce a prophylactic effect by raising a patient's threshold of vulnerability to relapse.