Now that at the Jakarta Forestry Congress it was announced on the behalf of the Indonesian government that a target area has been set to conserve 5% of the land area, eventually to be increased to 10%, the time has come to indicate how these areas are to be allocated. Botanical arguments are available as a guidance; they are drawn from established sources, including experience from work at the Rijksherbarium. A number of points are here given. 1. In Malesia, it is usually possible, clearly to distinguish between primary forest: rich in species, balanced as an ecosystem, complex, fragile, different from place to place, in which rarity of species prevails, slow in regeneration, irreplaceable within any foreseeable amount of time, and secondary forest: poor in species, an ecosystem in succession, simple, aggressive, consisting of common, widespread species, quick in regeneration, and entirely renewable. From the botanical point of view, secondary forest has no conservation value, only primary forest has.