Marine-derived fungi have proven to be a good source of structurally novel and biologically active secondary metabolites, which might be useful leads in the development of new pharmaceutical agents. In our continuing search for bioactive compounds from marine-derived fungi, we previously isolated a new anthracycline-derived pentacyclic metabolite, seragakinone A, from the mycelium of a fungus (K063), which was separated from an Okinawan marine red alga. Further investigation on extracts of the mycelium of the same fungus resulted in the isolation of two new peptides, dictyonamides A (1) and B (2). In this paper, we describe the isolation and structure elucidation of 1 and 2.