The objective of this study was to determine health protection measures, common diseases, herd leaving reasons, and health and artificial insemination costs based on the herd size of the farms registered to Izmir Cattle Breeders' Association (ICBA) in Odemiş raising Holstein cattles. The data were obtained from surveys with a total of 92 farms selected with proportional sampling method among the members of the ICBA. The farms were divided into three subgroups based on the cow numbers of the herds. The numbers of cows in subgroups were: i) 5-20 (55 farms), ii) 21-40 (29 farms), and iii) over 41 heads (8 farms). The ratio of insured cattle- farms in the ICBA was 14.1%. The ratio of farms taking health care measurements were quite variable such as for foot care 58.7%, oral administration of magnet 68.5%, and dehorning 94.6%. The majority of breeders (98.9% of which 85.9% with water and 13 % with dry cleaning) has maintained udder cleanness by washing with water before milking and 1.1% of those who cleaned udder did not wash the mammary lobes. Only 17.4% of the farms received a regular veterinary visit, whereas 82.6% of farmers called veterinary when needed. In the last year the most encountered disease in farms was common udder diseases (50.9%) followed by, calf diarrhea (15.7%), reproductive diseases (13.0%), foot and leg diseases (9.3%), and digestive system diseases (3.7%). The average rate of the farmers making mastitis treatment was 81.5 at the dry-off period. Total veterinary, medicine and artificial insemination costs per cow in first, second and third group farms were 482, 396 and 368 liters, respectively and the average was 445 liters in terms of milk quantity. In this study, it was determined that when the herd size is increased insuring the animals, there were improvements in keeping of health records, dehorning, foot caring, the use of disinfectants in udder cleaning, treating mastitis at dry-off, the latest milking cows with mastitis, making mastitis vaccine, taking regular veterinarians help, and disinfecting the barns. On the other hand, udder diseases, stillbirth rates and health care costs per cow were decreased.