There is no information concerning the contractile and detrusor cell properties of detrusor smooth muscle from neonatal exstrophy bladders (NE). The aim of this study was to examine these properties of NE and compare them to those with normal bladder (N) function.Following ethical approval and patient consent full thickness bladder samples were obtained from patients with NE and N. Detrusor strips were superfused at 37°C with HCO 3 /CO 2 buffered physiological solution. Nerve-mediated responses were elicited by electrical field stimulation. Muscle-mediated responses were generated by carbachol and a,bmethylene-ATP (ABMA). Tension was normalised to unit cross-sectional area (mN.mm -2 ). Data is presented as mean±s.d. Detrusor cells were isolated using collagenase and loaded with a Ca2+ indicator (fura-2). The 340/380 ratio, a direct measure of intracellular calcium [Ca2+]i changes was measured following addition of carbachol, ABMA, and KCl. Significance of differences (p<0.05) between means were examined by Student's t-test.Nerve-mediated were significantly less (0.8±0.3 vs 2.9±4.7 mN.mm -2 ), as were the muscle-mediated responses (5.4±3.6 vs 30.8±22.2) in samples from NE compared to N (n=5, 20 respectively). The NE strips however were more sensitive after addition of carbachol (EC 50 s; 1.8±0.5 vs 3.2±1.2). Following addition of carbachol, ABMA, and KCl to isolated cells, [Ca2+]i transients were observed. The 340/380 ratios were not statistically significantly different between NE and N bladders (carbachol; 0.4 vs 0.4, ABMA; 0.7 vs 0.8, KCl; 0.4 vs 0.4, n=9,15 respectively).The data show that contractile function is reduced in patients with NE compared to N. The detrusor cell function appears normal. Altered muscle-matrix interaction content and/or dysfunctional excitation-contraction coupling could play a role in this hypocontractility.