Excitotoxicity contributes to neuronal death and is involved in the pathogenesis of neurodegenerative disorders such as Alzheimer's disease (AD). In the present study, cryptotanshinone, an active ingredient from a Chinese plant, Salvia miltiorrhiza, was investigated to assess its neuroprotective effects against glutamate-induced toxicity in primary culture of rat cortical neurons. Cryptotanshinone reversed glutamate-induced neuronal toxicity, which was characterized by decreased cell viability, increased lactate dehydrogenase release, neuronal DNA condensation, and the alteration of the expression of Bcl-2 family proteins. The neuroprotective effects of cryptotanshinone could be blocked by LY294002 and wortmannin, two inhibitors of PI3K. The importance of the PI3K pathway was further confirmed by the activation of Akt and anti-apoptotic Bcl-2 by cryptotanshinone in a PI3K-dependent manner. These results suggest that cryptotanshinone protects primary cortical neurons from glutamate-induced neurotoxicity through the activation of PI3K/Akt pathway. Such neuroprotective effects may be of interest in AD and other neurodegenerative diseases.