ABSTRAK Tujuan penelitian ini ialah untuk mengetahui sebaran klorofil-a dan kualitas air di perairan Ujung Pancu, Aceh Besar. Penelitian ini dilakukan pada Bulan November hingga Desember 2017. Proses pengambilan sampel menggunakan metode purposive sampling pada 5 stasiun pengamatan dan analisis sampel menggunakan metode spektrofotometri. Hasil penelitian di Laboratorium Kimia Fakultas Keguruan dan Ilmu pendidikan menunjukkan bahwa, konsentrasi klorofil-a ialah berkisar antara 2,05 hingga 0,320 µg/l. Nitrat dan posfat berturut-turut berkisar antara 0,8 – 0,9 mg/l dan 0,019 – 0,036 mg/l. Kata kunci: Klorofil-a; Kualitas perairan; Ujung Pancu. ABSTRACT This research aims to figure out the distribution of chlorophyll-a and water quality at Ujung Pancu waters, Aceh Besar. This research was conducted from November to December 2017. The sampling used purposive sampling method at 5 observation stations. Samples were analyzed using spectrophotometric method. At Laboratory of Chemistry of Teacher Training Faculty. The results showed that the chlorophyll-a concentration was ranged from 2,05 to 0,320 μg/l. Nitrate and phosphate content were ranged from 0,8 to 0,9 mg/l and 0,019 – 0,036 mg /l respectively. Keyword: Chlorophyll-a; Water quality; Ujung Pancu.