Eight new porphinoids, tolyporphins B-I (2-9), along with the known tolyporphin A (1) have been isolated from a lipophilic extract of the Pacific cyanophyte, Tolypothrix nodosa. Their structures have been elucidated using 1- and 2-D NMR spectroscopic experiments and the tolyporphins showed varying activities in drug accumulation and competitive binding assays for multidrug resistance (MDR) reversal.