We assessed the validity of an Italian language version of the Epworth sleepiness scale (ESS). The translated ESS was compared to the multiple sleep latency test (MSLT), considered the gold standard for the diagnosis of excessive daytime sleepiness (EDS). Within the context of a multicentric national study on narcolepsy (Gruppo Italiano Narcolessia Studio Epidemiologico Nazionale, GINSEN) involving 17 Italian sleep centres, we compared the two diagnostic tests on 91 prospectively recruited subjects with suspected EDS (34 with narcolepsy, 16 with obstructive sleep apnea syndrome, 19 with idiopathic hypersomnia, and 22 with other sleep, neurologic or psychiatric disorders). ESS scores were inversely correlated with mean sleep latency values, as measured with MSLT (rho = -0.31, p<0.01). ESS cut-off scores with best sensitivity and specificity were 12 and 17. For the 5-min MSLT cut-off, sensitivity was 87% and 47% respectively; specificity 39% and 74%. For the 8-min MSLT cut-off, sensitivity was 84% and 49%; specificity 50% and 88%. The Italian version of the ESS is an easy-to-use form useful for preliminary screening of daytime sleepiness level in specialist settings.