Calcium channel blockers have been used in the treatment of primary and secondary Raynaud's phenomenon (RP), and a beneficial effect was often recorded. The efficacy of slow-releasing nicardipine was assessed in a clinically homogeneous series of RP without underlying diseases in a randomized, double blind, cross-over and placebo controlled trial. Out of twenty-one selected patients (18 women and 3 men, mean age 46 +/- 12 yrs) eighteen completed the study and three dropped out, one for inadequate compliance and two due to headache. After a three-week period, slow-releasing nicardipine (20 mg two times daily) was significantly more useful than placebo: the number of RP episodes per week decreased (p less than 0.02), severity of discomfort and hand disability scores, evaluated after single RP attack, clearly improved (p less than 0.005 and p less than 0.02, respectively). According to clinical improvement, time of peak flow after postischemic reactive hyperaemia test was significantly reduced only after nicardipine (p less than 0.01). These results show that slow-releasing nicardipine is generally well tolerated and can provide effective improvement in RP patients without underlying diseases.