Ahnfeltia plicata (Hudson) Fries, 1836, is a commercially important agar producer which occurs in the Magallanes region, characterized by an heteromorphic life-cycle. Several in vitro growth techniques have been used for the micropropagation of different genotypes of macroalgae. Nevertheless, there are no records of work undertaken with A. plicata. The objective of this research was for the development of in vitro growth techniques of A.plicata vegetative tissue for micropropagation using 2 plant growth substances: 6- Bencilaminopurine (BAP) and Indolacetic acid (IAA) under different culture conditions. Non reproductive gametophyte thalli from apical and intermediate portions were used, from where 5 mm explants were obtained. Plant growth substances were used in 3 concentrations: 0.1 mg/L, 1,0 ng/L and 5.0 mg/L, all prepared within a Provasoli culture media. The experiment was undertaken threefold for each hormone concentrate and for each explant, using n=4 for each growth Petri dish in two photoperiods 16:8 and 12:12, (light: darkness) with a temperature of 10°C and a light intensity of 9 - 10 ?mol seg-1 m-2. Monitoring and measurements for each explant were undertaken every seven days. It was observed that both plant growth substances enhanced growth of Ahnfeltia plicata. The growth media enriched with IAA enhanced the growth in polar regions of the A. plicata explants while the use of BAP showed both growth in polar regions and side branches. The explants regeneration process evidenced better results with BAP 1 mg/Lt with a photoperiod of 12:12 (light:darkness) The tissues grown in short photoperiods evidenced larger decoloration and a greater percentage of mortality

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