Thirty-six cases of feline urine marking problem were collected through the cooperation of veterinary practitioners in the Kanto, Chubu, and Kansai areas in Japan, for an assessment of the clinical effect of treatment with a synthetic analogue of a feline cheek gland pheromone-like product. The mean frequency of urine marking was 14.2 times/week (median, 10; range, 1-77) at pre-treatment week (preW), and decreased significantly from the first week of treatment, dropping to 4.2 times/week (median, 2; range, 0-44) at the fourth week of treatment. This effect continued until the fourth week after cessation of treatment. These 36 cases were divided into 3 groups based on the effectiveness of treatment as demonstrated in the fourth week of treatment; 37% was categorized as the totally eliminated group (urine marking was not seen), 40% as the reduced group (the frequency of urine marking was equal to or less than 50% that of the preW), and 23% as the unchanged group (the frequency of urine marking was more than 50% that of the preW). Effectiveness of treatment in these groups was 38%, 24%, and 38% at the fourth week after the cessation of treatment, respectively. The decreasing rate of urine marking was compared between cats with and without intercat aggression, and it was revealed that the frequency of marking was sustained at high level in cats with intercat aggression. These results suggest that this pheromone treatment is as effective in Japan as has been reported in other countries for solving feline urine marking problems.