It is difficult to make judgment on the status effects of cannabis toxicity on neuropsychological performance. Neuropsychological performance is a broad terminology, thus, careful classification of the neuropsychological domains must be undertaken. Possibility of some weaknesses in age and sex distribution is postulated, as well as less sensitivity in statistical analysis for sex data. Three main points are forwarded. First, several important domains from broad spectrum of neuropsychology are depicted. Second, positive and negative effects of cannabis are classified clearly. Third, the weaknesses of sample characteristic (i.e, age and sex distribution) are scrutinized.