From the methanolic extract of the Red Sea sponge Callyspongia sp. six new polyacetylenic compounds, aikupikanynes A-F, together with octahydrosiphonochalyne, were isolated and identified. Their structures, which comprise four hydrocarbons, two alcohols, and one unprecedented R-hydroxy carboxylic acid, were determined by extensive 1D and 2D NMR studies and mass spectral determinations.