Acetyl-L-carnitine produces a significant increase in the survival time-course of adult rat sensory neurons maintained in primary cultures up to 40 days. The analysis of our data suggests that 200 microM acetyl-L-carnitine added to the medium, slows down neuronal decay especially in the first 10 days in vitro, sparing a fraction of cells which would otherwise be lost. Patch-clamp recordings from these neurons show that superfusion with acetyl-L-carnitine (100-1000 microM) does not induce any membrane current. In addition an agonist muscarinic effect particularly concerning high-voltage activated calcium channel modulation appears to be ruled out. In conclusion our data favour the role of acetyl-L-carnitine in the trophism of sensory neurons in adult rats. In agreement with other in vivo experiments our data reinforce the hypothesis that this substance might be involved in reducing neuronal loss observed in nervous system aging.