RESUMEN
The aim of this work was to determine Giardia and Cryptosporidium levels in surface water used either as recreational or drinking water source, and to estimate the relationship with bacteriological and physicochemical parameters determining water quality. This study was carried out during 22 months, in Santa Fe and Santo TomÚ cities (Santa Fe Province, Argentina). Cryptosporidium from 100 of the recreational samples (44-2404 oocysts/100 l) and from 92 of water sources (< 20-539 oocysts/100 l) was detected, while Giardia was found in lower concentrations and frequencies: 72 (< 20-670 cysts/100 l) and 31 (< 20-65 cysts/100 l), respectively. Statistically significant relationships were found between these parasites and organic matter, turbidity and bacteriological indicators of contamination (Escherichia coli, streptococci, Enterococcus spp, Pseudomonas aeruginosa). These relationships, however, vary according to the sampling place, the source and levels of contamination.