Pulmonary Alveolar Macrophages (PAMs) are the initial phagocytic cells that encounter foreign material and particulates deposited in the terminal airways. The study of PAMs had been facilitated by its availability in Bronchoalveolar lavage (BAL) fluid by evaluation. Seventy healthy adult male (Rattus rattus norvegicus albinus), twenty_five weeks old. For each rat, the BAL was performed by tracheal cannulation and a total volume of 48ml phosphate-buffered saline (PBS; pH 7.4, 37°C) was installed in 8ml aliquots for 20 sec Different stains were used for cytological study including: PAMs morphology, PAMs count (without staining), differential BAL cells count and morphometry of PAMs by (Global Lab Image /2) software was used in this study. Cytochemical study of PAMs was done by the identification of esteratic activity which was demonstrated against the substrate a-naphthyl acetate (ANAE), the simultaneous azo-coupling method. Microspetro_photometry was used for studying the quantization of PAMs esterase cytochemistry.