Summary—In a study of 75 isolated human detrusor muscle strips, spontaneous contractions and an associated sustained rise in basal tension were observed in 43 (57%). Vasoactive intestinal polypeptide (VIP) caused significant reductions in the frequency and amplitude of spontaneous contractions and a fall in basal tension. The results suggest that VIP may have a role as an inhibitor of spontaneous activity in the human detruso