Antioxidant, cytotoxic, and antimicrobial activities of leaves, bark, and cone extracts of Alnus incana (L.) Moench ssp. incana and endemic species A. viridis (Chaix) DC ssp. viridis were evaluated. All extracts were found to be strong 1,1-diphenyl-2-picrylhydrazyl free radical scavengers, exhibiting 50% inhibitory concentration $(IC_{50})$ values of 3.3-18.9 ${mu}g/mL$, and also showed activity in inhibition of lipid peroxidation with $IC_{50}$ values ranging from 38.5 to 157.4 ${mu}g/mL$. A. incana and A. viridis extracts exhibited significant cytotoxic effects toward HeLa cells, with $IC_{50}$ values ranging from 26.02 to 68.5 ${mu}g/mL$. The most active extract of A. incana bark also contained great amounts of total phenolics (316.2 mg of gallic acid equivalents/g). In our experiment all extracts were virtually nontoxic on brine shrimps. Extracts were screened for activity against 15 microorganisms, and all extracts investigated showed antimicrobial activity. The most active were dry extracts of cones of A. incana and A. viridis with minimum inhibitory concentration values ranging from 0.117 to 0.129 mg/mL.