Aminophthalide derivatives of cytisine, anabasine, and salsoline were obtained in high yields via condensation of the alkaloids with o-formylbenzoic acid. Their structures were proven using H-1 and C-13 NMR spectroscopy and data from 2D COSY H-1-H-1 and HMQC H-1-C-13 spectra. Studies of their antimicrobial activity showed moderate antimicrobial activity of 3-(N-cytisin-1-yl)isobenzofuran-1(3H)-one and 3-(N-salsolin-1-yl)isobenzofuran-1(3H)-one against Gram-positive test strain Staphylococcus aureus ATCC 6538 and Gram-negative test strain Escherichia coli ATCC 25922.