Rabbit corpus cavernosum smooth muscle (RCCSM) cells express channels that produce Ca²⁺-activated Cl^- (I_ClCa) current, but low sensitivity to conventional antagonists have made its role in tone generation difficult to evaluate. We have re-examined this question using two new generation I_ClCa blockers, T16A_inh-A01 and CaCC_inh-A01. Isolated RCCSM cells were studied using the perforated patch method. Current-voltage protocols revealed both L-type Ca²⁺ current and I_ClCa. T16A_inh-A01 and CaCC_inh-A01 (10 M) reduced I_ClCa by ~85%, while 30 M abolished it. L-type Ca²⁺ current was unaffected by 10 M CaCC_inh-A01, but was reduced by 50% at 30 M CaCC_inh-A01, 46% at 10 M T16A_inh-A01 and 78% at 30 M T16A_inh-A01. Both drugs reduced spontaneous isometric tension in RCCSM strips, by 60-70% at 10 M and >90% at 30 M. Phenylephrine (PE)-enhanced tension was also reduced (ED₅₀ = 3 μM, CaCC_inh-A01; 14 μM, T16A_inh-A01). CaCC_inh-A01 10 M had little effect on 60 mM KCl contractures, though they were reduced by 30 M CaCC_inh-A01 and T16A_inh-A01 (10 M & 30 M) consistent with their effects on L-type Ca²⁺ current. Both drugs also reversed the stimulatory effect of PE on intracellular Ca²⁺ waves, studied with laser scanning confocal microscopy in isolated RCCSM cells. Although both drugs were effective blockers of I_ClCa, the effect of T16A_inh-A01 on L-type Ca²⁺ current preclude its use for evaluating the role of I_ClCa in tone generation. However, 10 μM CaCC_inh-A01 selectively blocked I_ClCa vs L-type Ca²⁺ current and reduced spontaneous and PE-induced tone, suggesting that I_ClCa is important in maintaining penile detumescence.