Two different morphologies of porous layers were observed in (100)-oriented n-InP anodically etched in an aqueous solution of HCl. At high current density (60 mA/cm(2)) anodization leads to the formation of so-called current-line oriented pores. When the current density decreased to values lower than 5 mA/cm(2) the morphology of the porous layers sharply changed and the pores began to grow along definite <111> crystallographic directions.