To assess the toxicity of urine samples on human fibroblast cell monolayer using Shell-vial technique for cytomegalovirus antigen detection. A total of 227 urine samples were processed, inoculated on Shell-vial simultaneously, being either diluted (1:1) and non diluted in transport media. After 24-48 hours incubation, the fibroblast cells monolayer was stained using fluorescein-marked monoclonal anti-cytomegalovirus antibodies. Cytomegalovirus was detected in 9.6% of samples inoculated with diluted urine, and in 5.2% of samples inoculated with non-diluted urine. Destruction of monolayer cells was seen in 13.2 and 22.4, respectively. With Shell-vial technique for detecting cytomegalovirus in urine samples, a high number of positive results was obtained using diluted urine. Also a significant minor destruction of cells monolayer was observed with the same inoculum.