There is a growing interest in alternative diets such as vegan or lacto-ovo vegetarian diet. The choice is made mainly for ethical, health reasons or both. Creatinine is a waste product of creatine phosphate metabolism in muscles, and the excretion rate is relatively constant. Forty-nine participants were tested in total: 5 lacto-ovo vegeterians, 14 vegans, and 30 omnivores. To compare the groups, all participants had a similar diet consisting of bread, bran flakes and wheat bran. The creatinine level was measured before the initiation of the diet in the first morning void, and in the sample of 24-h urine. The results confirmed slightly higher mean creatinine levels in males (1139 ± 517 mg/L), compared to females
(901 ± 539 mg/L). Regular consumption of different diets did not show   statistically significant differences in datasets on either first void or 24-h samples. The highest median result after 24-h was determined in lacto-ovo vegetarians (2175 mg/L), followed by omnivores (1328 mg/L), while vegans had the lowest median (1235 mg/L). Based on these results, there is no evidence that the vegetarian or vegan lifestyle influences the creatinine excretion rate.