The clinical features of salmonellosis and prevalence of salmonella serogroups in calves were studied on one hundred and thirty two suspected calves in dairy farms around Tehran. Clinical examinations were carried out and the faecal or tissue (if calve was euthanized or dead) samples were collected for bacterial culture. The results were analyzed with Chi-square statistical test. Salmonella spp was isolated from 18 samples of 132(13.6%). Salmonella isolates belonged to 4 serogroups D, B, Cl and C2. Clinical signs Observed in 6 forms: chronic entritis(33.3%), septicemia(27.8%), Acute enteritis(22 %), dry gangrene of exterimities( 5.5 % ), pneumoenteritis( 5.5 % ) and polyarthritis( 5.5 % ). Eight of 18 salmonelleic calves (44.4%) died and 7 (38.9%) euthanized because of prolonging disease and not response to treatment. Occurrence of salmonellosis was signifiantly higher in calves with 1.5 to 3 month of ages (p <0.05). The prevalence of salmonellosis was higher in summer and winter and was more in calves that were held in hutches, but the differences were not significant. Most common clinical forms of salmonellosis were chronic enteritis, acute enteritis and septicemia. Most of salmonella isolates belonged to serogroup D (61.2%).Considering Other studies and results of this research, the serogroup D salmonella apear to be the most common cause of salmonellosis in calves in dairy farms around Tehran.