To find the distance between the two points \( A(1, 5) \) and \( B(5, 2) \), we can use the distance formula:
\[ d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2} \]
where \( (x_1, y_1) = (1, 5) \) and \( (x_2, y_2) = (5, 2) \).
Substituting the values into the formula:
\[ d = \sqrt{(5 - 1)^2 + (2 - 5)^2} \]
Calculating the differences:
\[ d = \sqrt{(4)^2 + (-3)^2} \] \[ d = \sqrt{16 + 9} \] \[ d = \sqrt{25} \] \[ d = 5 \]
Therefore, the distance between the two points is \( \boxed{5} \) units.