The chloroform soluble (CS) and ethyl acetate (ES) soluble alkaloidal extracts from the seeds of Leucaena leucocephala Lam. (de Witt) were tested for their analgesic, anthelminthic, mutagenic, antimutagenic and pharmacological activities. The CS alkaloidal extract is analgesic at a dose of 5 mg/20 g mouse as it showed a comparable result to mefenamic acid using the acetic acid-induced writhing method. An in vitro test for anthelminthic activity using Ascaris suum showed that the CS alkaloidal extract gave a comparable result to mebendazole (Antiox) at a concentration of 5 mg/mL. Results of the micronucleus test, an in vivo method, showed that both the CS and ES alkaloidal extracts were not mutagenic but instead exhibited antimutagenic activities at 0.5 mg/20 g mouse. The CS-and ES-soluble alkaloidal extracts reduced the number of micronucleated polychromatic erythrocytes induced by tetracycline, a known mutagen, by 67.0% and 71.2%, respectively. Preliminary pharmacological screening showed that both extracts caused a relative depression in the central nervous system as evidenced by a decrease in respiratory rate and depth and a decrease in motor activity.