In a homogeneous group of French Caucasian patients with schizophrenia (N=102, 66 men and 36 women), we found distinct results. Information was available from a direct standardized interview (the Diagnostic Interview for Genetic Studies), prospectively documented medical files (with urinary dose at index admission), practitioners, and family interviews (1). Twenty-seven schizophrenic patients were characterized as "cannabis sensitive" since they had their first psychotic episode less than 6 months after the onset of cannabis use or less than 3 months after the onset of daily or heavy consumption and/or displayed prominent delusions or hallucinations when using cannabis. Cannabis-sensitive patients were slightly younger at the first psychotic episode than the remaining patients (mean=20.4, SD=3.1, versus mean=22.5, SD=4.9) (t=2.04, df=100, p=0.04). The positive schizophrenic symptom profile, evaluated with the Positive and Negative Syndrome Scale (2) adjusted on the duration of disease, was significantly more marked in cannabis-sensitive patients (mean=20.8, SD=5.3, versus mean=15.9, SD=5.2) (F=17.8, df=1, 99, p=10–4), even in men only or when the recent users (within the year, N=7) were withdrawn. No difference was seen regarding the negative symptoms (mean=23.6, SD=8.6, versus mean=22.4, SD=8.7) (F=0.73, df=1, 99, p=0.39).