Longitudinal studies for a period of a year were conducted on five variables with eight normal adult male cats. The variables were adrenaline, noradrenaline, glucocorticoid hormones, body weight, and food intake. Body weight and food intake were determined once every two weeks for the period of a year, and the urinary content of adrenaline, noradrenaline and glucocorticoid hormones were determined once a month for the same period. The annual trend was viewed in three ways, by plotting the means, by a “cosinor"‐like coordinate plot, and by a periodic regression technique. The results indicate that the periodic regression technique provided a good representation of the data in all cases, but the cosinor plot had limited applicability. In the special case when the annual sine curve accounted for all the trend, the cosinor and periodic regression technique are equivalent. Limitations of the cosinor representation involve the non‐sinusoidal shape of the data and the ubiquity of bimodal patterns, a ubiquity existing for both circadian and circannual periods. The temporal organization of the cat involves an annual phase map, and the associated physiological mechanisms and adaptive significance are suggested as important questions.