The objective of this study was to present clinical and electroencephalographic findings in 18 cases with late infantile neuronal ceroid lipofuscinoses, focusing on features that assist early diagnosis. Clinical and EEG findings have been described in the past for classic types, but several variants have recently been reported. The authors reviewed the clinical and EEG findings of 18 childhood onset neuronal ceroid lipofuscinoses cases. In the late infantile neuronal ceroid lipofuscinoses type, both typical and variant cases have been observed. In this type, the presence of a particular pseudoperiodic EEG pattern that we found in 15/18 patients and observed in the first stages of the disease could be useful in early diagnosis, especially if associated with the absence of sleep spindles. A precise nosological classification, based both on clinical and instrumental findings is the prerequisite for a correct genotype-phenotype correlation that could greatly improve our knowledge of this disease, providing a better understanding of pathogenesis and increasing our ability to treat it.