The Present Wk. Was Carried Out with the Aim to Docum. the Composition of the Flowering Plants of the Reg. Sanctuary of Piura manglares S. Pedro, of Vice-Sechura. Its Importance Resides in That It Is the Most S. Mangrove Forest in the Pac. of S. Amer.. the Stud. Was Carried Out from April of the 2000 until February of the 2004. for the Realization of the Present Wk. Periodic Visits Every Two Months to the Pl. Were Undertaken, the Plants Were Collected under the Std. Procedures. the Samples Were Determined in the Pl. and Some Were Taken to the Lab. of Bot. of the Natl. Univ. of Piura and the Lab. of Phanerogamic Bot. of the Natl. Univ. of Trujillo for Their Definitive Determination, Then the Samples Were Deposited in the Herbarium in Form. of the Natl. Univ. of Piura. the Mangrove Forest Primarily Consists of Trees and Shrubs of Avicennia Germinans L. mangle Prieto. the Present Inventory Reports 44 Species of Phanerogams Belonging to 36 Genera in 21 Families from the Mangrove.