Seasonal biomass variation, agar yield and some agar properties of Pterocladia capillacea and Hypnea musciformis were examined during the period from July 2003 to June 2004. The maximum biomass values of both studied algae were recorded during winter and the minimum values were obtained during spring and summer. Agar yield of P. capillacea varied from a minimum of 26.6% (dry weight) in August, to a maximum value of 35.6% in October, while that of H. musciformis varied from a minimum of 15.3% at June, to a maximum of 24% at December. The maximum agar gel strengths were recorded at July (being 225 and 158 gcm^-2 of P. capillacea and H. musciformis, respectively). Gelling and melting temperatures showed significant seasonal variation for both studied algal species. Agar yield and quality of P. capillacea and H. musciformis were within the range of accepted commercial values. Yield and gel properties of agar extracted from H. musciformis were comparable with those obtained from P. capillacea. Results also indicated that H. musciformis can be considered as a good candidate for commercial agar use.