Medical data mining is so challenging. In this paper, we propose a new data mining algorithm called GAJA2, which is a derivation of GAJA [1]. We apply GAJA2 to mine Acute Inflammations data set, a medical data set got from UCI machine learning repository 2009[2]. This data set is about symptoms and diagnosis of two diseases of urinary system which are inflammation of urinary bladder and Nephritis of renal pelvis origin. The results show that knowledge mined by using GAJA2 is very interesting. We compare the results from GAJA2 with GAJA and Rough Set Theory. We found that the results from GAJA2 can be used by the experts in the fields and are very much easier to understand than from GAJA and Rough Set Theory.