OBJECTIVES: Little is known about cancer (CA) in hospitalization, cost and outcomes in transitional countries. We studied this in a multicentric hospital study in Argentina. METHODS: Adult CA, hospital direct costs, re-admissions (ReH <30 days) and deaths in 1 yr output of 3 academic hospitals. Cost and results,  harmonized according HCUPS (USA) terminology groupers,  of primary (1Dx), and secondary diagnosis (2Dx) for each CCS code (Clinical Classification Software-CCS single level-SL, 2009). Total costs (CT$), mean costs (SD) and median per discharge cost ($, 25P-75P-percentiles), in Itl.$ PPP, (UN Data: 1Arg$ = 1.608 PPP, 2008). CA defined as (#CCS [descriptive term]), including from  CCS #11 [head and neck CA] to #44 [Neoplasms of unspecified nature or uncertain behavior] and CCS 45 [Maintenance chemotherapy; radiotherapy--QT;RT]. Readmisions (ReH) <30 days and hospital deaths were obtained. RESULTS: Among 45 466 ≥ 19 yrs.old, CA was found in 6 282, 13,81%(95%CI 13,50-14,14) Dx1; CCS 11-45 (F= 49,33%) (individual CA data not shown) while QT;RT (# 45) = 2 520 disch., 5,54% (4,75-5,15). Among CCS 45 [QT;RT] en 1Dx, CCS #11-44 in any 2Dx up to 5 2Dx code adds 3,046 disch; adding CA codes 1Dx +2Dx = 9.298 discharges (20,45%, 20,08-20,82). Among CCS en 1Dx, CT $ = I $ PPP  64 088 727; mean: I$ 17,035; SD: I$ 4,276; median: I$ 8,897 (25P 4,042; 75 P 19,601). ReH <30 d = 485 (1,06 %, 0.97-1,16); while QT-RT (#45) ReH< 30 = 1,754 (3,86%, 3,68-4,04). Case fatality rate for CCS 11-44 was 3,27%,(2,86-3,74), and for CCS 45 was 0,17%,( 0,06-0,45).   CONCLUSIONS: CA burden among hospital discharges, and its costs, case fatality, and readmisions were obtained for the first time in Argentina. QT-RT as a first Dx is close to half of discharges, and showing CA en 2Dx behaves differently in ReH and mortality. An iceberg phenomenon of CA in 2Dx emerges.