Samples of Eisenia arbórea from Baja California Sur, México collected in November 2002 and March 2003 were studied. The following parameters were analyzed separately from blades and stipes: moisture, ash, mannitol, fat and crude fiber. Alginate was isolated and the following quality parameters were obtained: yield (22.4-23.3%), color (> 4) and viscosity (793- 2,210 m-Pa-s in 1% solution). No significant differences were obtained between two months, except for viscosity and crude fiber. Significant differences were obtained when comparing blades and stipes in viscosity, mannitol, ash and fat, while for yield, moisture and crude fiber no significant differences were obtained. FTIR spectroscopy showed that alginate from E. arbórea contained similar amounts of mannuroic and guluronic acids (M/G = 1)