<jats:p>Twenty isoquinoline alkaloids were identified in the aerial part of <jats:italic>Fumaria densiflora</jats:italic> DC. In addition to bicuculline, densiflorine, fumaritine, fumariline, scoulerine, coptisine, cryptopine, parfumine, protopine, and sinactine which have been found previously, the following alkaloids were isolated for the first time from this species: adlumine, fumaricine, fumaritridine, fumarophycine, fumarofine, corytuberine, <jats:italic>cis</jats:italic>-<jats:italic>N</jats:italic>-methylstylopinium iodide, stylopine, and two new 1-benzylisoquinoline alkaloids, viz. fumaflorine and fumaflorine methyl ester. The cytoprotectivity of extracts of <jats:italic>F</jats:italic>. <jats:italic>densiflora </jats:italic>and <jats:italic>F. officinalis</jats:italic>, and that of protopine, cryptopine, and parfumine was tested on primary cultures of rat hepatocytes intoxicated with carbon tetrachloride. The cytoprotective effect of the extracts is associated with the alkaloids.