A short overview is given of the evidence supporting the existence of subtypes of 5-HT1 receptors. As 5-HT1 receptors were first described using radioligand binding studies, a brief description of 5-HT1A, 5-HT1B, 5-HT1C and 5-HT1D receptor binding is given. Then, recent data obtained in biochemical, electrophysiological, behavioural and other functional studies is compared to results obtained in radioligand binding studies. The paper shows that functional correlates do indeed exist for subtypes of 5-HT1 recognition sites; moreover, these are markedly different from the effects mediated by 5-HT2 (5-HT D) or 5-HT3 (5-HT M) receptors.