This study was undertaken to investigate the efficacy of prehydration with crystalloids or colloids for preventing spinal anaesthesia-induced hypotension in elderly normotensive and hypertensive patients. Eighty physical status ASA I-III elderly patients were enrolled in this study, receiving spinal anesthesia. Forty consecutive normotensive patients randomly assigned to receive fluid preloading 5ml kg-1 i.v either crystalloid (Group N/RL, n=20) or colloid solution (Group N/Coll, n=20), and forty consecutive hypertensive patients were treated in similar manner (Group H/RL, n=20, Group H/Coll, n=20). Systolic (SAP) and diastolic (DAP) arterial pressure were recorded before fluid preloading (T1-baseline), before spinal anesthesia (T2), 10min (T3), 30 min (T4) and 60 min (T5) after local anesthetic’s spinal administration. SAP and DAP decreased significantly (p<0.05 – p<0.01) at T4, T5 interval compared to baseline in all groups. In hypertensive patients reduction of SAP and DAP was greater with crystalloids. In normotensive patients significant reduction of SAP and DAP was noted at T4, T5 interval, but it was similar for both regimens. Conclusions: Fluid pretreatment with 5ml/kg crystalloids or colloids did not prevent the incidence of hypotension after spinal anesthesia. Colloid prehydration seems to moderate this kind of hypotension compared to crystalloid solution in hypertensive patients.