Two new compounds, a diterpenoid and an anthraquinone, as well as an indane derivative, which is reported as a natural product for the first time, have been isolated from the cells of the cultured cyanobacterium Nostoc commune (EAWAG 122b) by means of bioguided isolation. The structures were determined by spectroscopic methods, mainly NMR, infrared spectroscopy, and mass spectrometry. All isolates exhibit antibacterial activity.